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<div class="section" id="utilities">
<h1>Utilities<a class="headerlink" href="#utilities" title="Permalink to this headline"></a></h1>
<p>The utility functions provide a large assortment of common utility functions
required to write dapps, process user input and format data.</p>
<hr class="docutils" />
<div class="section" id="addresses">
<h2>Addresses<a class="headerlink" href="#addresses" title="Permalink to this headline"></a></h2>
<p>There are <a class="reference internal" href="notes.html#checksum-address"><span class="std std-ref">several formats</span></a> available to represent Ethereum
addresses and various ways they are determined.</p>
<dl class="docutils" id="utils-getaddress">
<dt><sup>utils</sup> . getAddress ( address ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Address</sup></dt>
<dd>Normalize any supported address-format to a <a class="reference internal" href="notes.html#checksum-address"><span class="std std-ref">checksum address</span></a>.</dd>
<dt><sup>utils</sup> . getIcapAddress ( address ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Normalize any supported address-format to a <a class="reference internal" href="notes.html#icap-address"><span class="std std-ref">ICAP address</span></a>.</dd>
<dt><sup>utils</sup> . getContractAddress ( transaction ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Address</sup></dt>
<dd>Computes the contract address of a contract deployed by <em>transaction</em>. The only
properties used are <em>from</em> and <em>nonce</em>.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id4">
<div class="code-block-caption"><span class="caption-text"><em>convert between address formats</em></span><a class="headerlink" href="#id4" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">address</span> <span class="o">=</span> <span class="s2">&quot;0xd115bffabbdd893a6f7cea402e7338643ced44a6&quot;</span><span class="p">;</span>
<span class="kd">let</span> <span class="nx">icapAddress</span> <span class="o">=</span> <span class="s2">&quot;XE93OF8SR0OWI6F4FO88KWO4UNNGG1FEBHI&quot;</span><span class="p">;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">getAddress</span><span class="p">(</span><span class="nx">address</span><span class="p">));</span>
<span class="c1">// &quot;0xD115BFFAbbdd893A6f7ceA402e7338643Ced44a6&quot;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">getAddress</span><span class="p">(</span><span class="nx">icapAddress</span><span class="p">));</span>
<span class="c1">// &quot;0xD115BFFAbbdd893A6f7ceA402e7338643Ced44a6&quot;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">getAddress</span><span class="p">(</span><span class="nx">address</span><span class="p">,</span> <span class="kc">true</span><span class="p">));</span>
<span class="c1">// &quot;XE93OF8SR0OWI6F4FO88KWO4UNNGG1FEBHI&quot;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">getAddress</span><span class="p">(</span><span class="nx">icapAddress</span><span class="p">,</span> <span class="kc">true</span><span class="p">));</span>
<span class="c1">// &quot;XE93OF8SR0OWI6F4FO88KWO4UNNGG1FEBHI&quot;</span>
</pre></div>
</div>
</div>
<div class="literal-block-wrapper docutils container" id="id5">
<div class="code-block-caption"><span class="caption-text"><em>determine a contract address</em></span><a class="headerlink" href="#id5" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="c1">// Ropsten: 0x5bdfd14fcc917abc2f02a30721d152a6f147f09e8cbaad4e0d5405d646c5c3e1</span>
<span class="kd">let</span> <span class="nx">transaction</span> <span class="o">=</span> <span class="p">{</span>
<span class="nx">from</span><span class="o">:</span> <span class="s1">&#39;0xc6af6e1a78a6752c7f8cd63877eb789a2adb776c&#39;</span><span class="p">,</span>
<span class="nx">nonce</span><span class="o">:</span> <span class="mi">0</span>
<span class="p">};</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">getContractAddress</span><span class="p">(</span><span class="nx">transaction</span><span class="p">));</span>
<span class="c1">// &quot;0x0CcCC7507aEDf9FEaF8C8D731421746e16b4d39D&quot;</span>
</pre></div>
</div>
</div>
<hr class="docutils" />
</div>
<div class="section" id="arrayish">
<span id="id1"></span><h2>Arrayish<a class="headerlink" href="#arrayish" title="Permalink to this headline"></a></h2>
<p>An arrayish object is used to describe binary data and has the following conditions met:</p>
<blockquote>
<div><ul class="simple">
<li>has a <em>length</em> property</li>
<li>has a value for each index from 0 up to (but excluding) <em>length</em></li>
<li>has a valid byte for each value; a byte is an integer in the range [0, 255]</li>
<li>is <strong>not</strong> a string</li>
</ul>
</div></blockquote>
<p><strong>Examples:</strong> <code class="docutils literal notranslate"><span class="pre">Buffer</span></code>, <code class="docutils literal notranslate"><span class="pre">[</span> <span class="pre">1,</span> <span class="pre">2,</span> <span class="pre">3</span> <span class="pre">]</span></code>, <code class="docutils literal notranslate"><span class="pre">Uint8Array</span></code></p>
<dl class="docutils">
<dt><sup>utils</sup> . isArrayish ( object ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Returns true if <em>object</em> can be treated as an arrayish object.</dd>
<dt><sup>utils</sup> . arrayify ( hexStringOrBigNumberOrArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Uint8Array</sup></dt>
<dd>Returns a Uint8Array of a hex string, BigNumber or of an <a class="reference internal" href="#arrayish">Arrayish</a> object.</dd>
<dt><sup>utils</sup> . concat ( arrayOfHexStringsAndArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Uint8Array</sup></dt>
<dd>Return a Uint8Array of all <em>arrayOfHexStringsAndArrayish</em> concatenated.</dd>
<dt><sup>utils</sup> . padZeros ( typedUint8Array, length ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Uint8Array</sup></dt>
<dd>Return a Uint8Array of <em>typedUint8Array</em> with zeros prepended to <em>length</em> bytes.</dd>
<dt><sup>utils</sup> . stripZeros ( hexStringOrArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Uint8Array</sup></dt>
<dd>Returns a Uint8Array with all leading zero <strong>bytes</strong> striped.</dd>
</dl>
<hr class="docutils" />
</div>
<div class="section" id="big-numbers">
<span id="bignumber"></span><h2>Big Numbers<a class="headerlink" href="#big-numbers" title="Permalink to this headline"></a></h2>
<p>A BigNumber is an immutable object which allow accurate math operations
on values larger than <a class="reference internal" href="notes.html#ieee754"><span class="std std-ref">JavaScript can accurately handle</span></a>
can safely handle. Also see: <a class="reference internal" href="#constants"><span class="std std-ref">Constants</span></a></p>
<dl class="docutils">
<dt><sup>prototype</sup> . add ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Return a new BigNumber of this plus <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . sub ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Return a new BigNumber of this minus <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . mul ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Return a new BigNumber of this times <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . div ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Return a new BigNumber of this divided by <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . mod ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Return a new BigNumber of this modulo <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . maskn ( bits ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Return a new BigNumber with the number of <em>bits</em> masked.</dd>
<dt><sup>prototype</sup> . eq ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Return true if this is equal to <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . lt ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Return true if this is less than <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . lte ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Return true if this is less or equal to <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . gt ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Return true if this is greater than <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . gte ( otherValue ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Return true if this is greater than or equal to <em>otherValue</em>.</dd>
<dt><sup>prototype</sup> . isZero ( ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Return true if this is equal to zero.</dd>
<dt><sup>prototype</sup> . toNumber ( ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>number</sup></dt>
<dd><p class="first">Return a JavaScript number of the value.</p>
<p class="last">An error is thrown if the value is outside the safe range for JavaScript
IEEE 754 64-bit floating point numbers (over 53 bits of mantissa).</p>
</dd>
<dt><sup>prototype</sup> . toString () &nbsp; <sup>=&gt;</sup> &nbsp; <sup>string</sup></dt>
<dd>Return a decimal string representation.</dd>
<dt><sup>prototype</sup> . toHexString ( ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Return a hexstring representation of the value.</dd>
</dl>
<div class="section" id="creating-instances">
<h3>Creating Instances<a class="headerlink" href="#creating-instances" title="Permalink to this headline"></a></h3>
<dl class="docutils">
<dt><sup>utils</sup> . bigNumberify ( value ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd><p class="first">Returns a BigNumber instance of <em>value</em>. The <em>value</em> may be anything that can
reliably be converted into a BigNumber:</p>
<table border="1" class="last docutils">
<colgroup>
<col width="33%" />
<col width="27%" />
<col width="39%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head">Type</th>
<th class="head">Examples</th>
<th class="head">Notes</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td>decimal string</td>
<td><code class="docutils literal notranslate"><span class="pre">&quot;42&quot;</span></code>, <code class="docutils literal notranslate"><span class="pre">&quot;-42&quot;</span></code></td>
<td>&#160;</td>
</tr>
<tr class="row-odd"><td>hexadecimal string</td>
<td><code class="docutils literal notranslate"><span class="pre">&quot;0x2a&quot;</span></code>, <code class="docutils literal notranslate"><span class="pre">&quot;-0x2a&quot;</span></code></td>
<td>case-insensitive</td>
</tr>
<tr class="row-even"><td>numbers</td>
<td><code class="docutils literal notranslate"><span class="pre">42</span></code>, <code class="docutils literal notranslate"><span class="pre">-42</span></code></td>
<td>must be witin the <a class="reference external" href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger">safe range</a></td>
</tr>
<tr class="row-odd"><td><a class="reference internal" href="#arrayish"><span class="std std-ref">Arrayish</span></a></td>
<td><code class="docutils literal notranslate"><span class="pre">[</span> <span class="pre">30,</span> <span class="pre">252</span> <span class="pre">]</span></code></td>
<td>big-endian encoding</td>
</tr>
<tr class="row-even"><td>BigNumber</td>
<td>any other BigNumber</td>
<td>returns the same instance</td>
</tr>
</tbody>
</table>
</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id6">
<div class="code-block-caption"><span class="caption-text"><em>examples</em></span><a class="headerlink" href="#id6" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">gasPriceWei</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">bigNumberify</span><span class="p">(</span><span class="s2">&quot;20902747399&quot;</span><span class="p">);</span>
<span class="kd">let</span> <span class="nx">gasLimit</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">bigNumberify</span><span class="p">(</span><span class="mi">3000000</span><span class="p">);</span>
<span class="kd">let</span> <span class="nx">maxCostWei</span> <span class="o">=</span> <span class="nx">gasPriceWei</span><span class="p">.</span><span class="nx">mul</span><span class="p">(</span><span class="nx">gasLimit</span><span class="p">)</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="s2">&quot;Max Cost: &quot;</span> <span class="o">+</span> <span class="nx">maxCostWei</span><span class="p">.</span><span class="nx">toString</span><span class="p">());</span>
<span class="c1">// &quot;Max Cost: 62708242197000000&quot;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="s2">&quot;Number: &quot;</span> <span class="o">+</span> <span class="nx">maxCostWei</span><span class="p">.</span><span class="nx">toNumber</span><span class="p">());</span>
<span class="c1">// throws an Error, the value is too large for JavaScript to handle safely</span>
</pre></div>
</div>
</div>
<hr class="docutils" />
</div>
</div>
<div class="section" id="bytes32-strings">
<span id="bytes32string"></span><h2>Bytes32 Strings<a class="headerlink" href="#bytes32-strings" title="Permalink to this headline"></a></h2>
<p>Often for short strings, it is far more efficient to store them as
a fixed, null-terminated bytes32, instead of a dynamic length-prefixed
bytes.</p>
<dl class="docutils">
<dt><sup>utils</sup> . formatBytes32String ( text ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd><p class="first">Returns a <a class="reference internal" href="#hexstring"><span class="std std-ref">hex string</span></a> representation of <em>text</em>, exactly
32 bytes wide. Strings <strong>must</strong> be 31 bytes or shorter, or an exception
is thrown.</p>
<p class="last"><strong>NOTE:</strong> Keep in mind that UTF-8 characters outside the ASCII range can
be multiple bytes long.</p>
</dd>
<dt><sup>utils</sup> . parseBytes32String ( hexStringOrArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>string</sup></dt>
<dd>Returns <em>hexStringOrArrayish</em> as the original string, as generated by <code class="docutils literal notranslate"><span class="pre">formatBytes32String</span></code>.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id7">
<div class="code-block-caption"><span class="caption-text"><em>example</em></span><a class="headerlink" href="#id7" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">text</span> <span class="o">=</span> <span class="s2">&quot;Hello World!&quot;</span>
<span class="kd">let</span> <span class="nx">bytes32</span> <span class="o">=</span> <span class="nx">ethers</span><span class="p">.</span><span class="nx">utils</span><span class="p">.</span><span class="nx">formatBytes32String</span><span class="p">(</span><span class="nx">text</span><span class="p">)</span>
<span class="c1">// &quot;0x48656c6c6f20576f726c64210000000000000000000000000000000000000000&quot;</span>
<span class="kd">let</span> <span class="nx">originalText</span> <span class="o">=</span> <span class="nx">ethers</span><span class="p">.</span><span class="nx">utils</span><span class="p">.</span><span class="nx">parseBytes32String</span><span class="p">(</span><span class="nx">bytes32</span><span class="p">)</span>
<span class="c1">// &quot;Hello World!&quot;</span>
</pre></div>
</div>
</div>
<hr class="docutils" />
</div>
<div class="section" id="constants">
<span id="id2"></span><h2>Constants<a class="headerlink" href="#constants" title="Permalink to this headline"></a></h2>
<dl class="docutils">
<dt><sup>ethers . constants</sup> . AddressZero</dt>
<dd>The address <code class="docutils literal notranslate"><span class="pre">0x0000000000000000000000000000000000000000</span></code>.</dd>
<dt><sup>ethers . constants</sup> . HashZero</dt>
<dd>The bytes32 <code class="docutils literal notranslate"><span class="pre">0x0000000000000000000000000000000000000000000000000000000000000000</span></code>.</dd>
<dt><sup>ethers . constants</sup> . MaxUint256</dt>
<dd>The bytes32 <code class="docutils literal notranslate"><span class="pre">0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff</span></code>.</dd>
<dt><sup>ethers . constants</sup> . NegativeOne</dt>
<dd>The <a class="reference internal" href="#bignumber"><span class="std std-ref">BigNumber</span></a> <code class="docutils literal notranslate"><span class="pre">bigNumberify(-1)</span></code>.</dd>
<dt><sup>ethers . constants</sup> . Zero</dt>
<dd>The <a class="reference internal" href="#bignumber"><span class="std std-ref">BigNumber</span></a> <code class="docutils literal notranslate"><span class="pre">bigNumberify(0)</span></code>.</dd>
<dt><sup>ethers . constants</sup> . One</dt>
<dd>The <a class="reference internal" href="#bignumber"><span class="std std-ref">BigNumber</span></a> <code class="docutils literal notranslate"><span class="pre">bigNumberify(1)</span></code>.</dd>
<dt><sup>ethers . constants</sup> . Two</dt>
<dd>The <a class="reference internal" href="#bignumber"><span class="std std-ref">BigNumber</span></a> <code class="docutils literal notranslate"><span class="pre">bigNumberify(2)</span></code>.</dd>
<dt><sup>ethers . constants</sup> . WeiPerEther</dt>
<dd>The <a class="reference internal" href="#bignumber"><span class="std std-ref">BigNumber</span></a> <code class="docutils literal notranslate"><span class="pre">bigNumberify(&quot;1000000000000000000&quot;)</span></code>.</dd>
<dt><sup>ethers . constants</sup> . EtherSymbol</dt>
<dd>The Greek character Xi, used as the symbol for <em>ether</em>.</dd>
</dl>
</div>
<hr class="docutils" />
<div class="section" id="cryptographic-functions">
<h2>Cryptographic Functions<a class="headerlink" href="#cryptographic-functions" title="Permalink to this headline"></a></h2>
<div class="section" id="elliptic-curve">
<h3>Elliptic Curve<a class="headerlink" href="#elliptic-curve" title="Permalink to this headline"></a></h3>
<dl class="docutils">
<dt><sup>utils</sup> . computeAddress ( publicOrPrivateKey ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Address</sup></dt>
<dd>Computes the Ethereum address given a public key or private key.</dd>
<dt><sup>utils</sup> . computePublicKey ( publicOrPrivateKey [ , compressed <sup>= false</sup> ] ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the public key for <em>publicOrPrivateKey</em>, optionally <em>compressed</em>. If
<em>publicOrPrivateKey</em> is a public key, it may be either compressed or uncompressed.</dd>
<dt><sup>utils</sup> . recoverAddress ( digest , signature ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Address</sup></dt>
<dd>Returns the Ethereum address by using ecrecover with the <em>digest</em> for the
<em>signature</em>.</dd>
<dt><sup>utils</sup> . recoverPublicKey ( digest , signature ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Returns the public key by using ecrecover with the <em>digest</em> for the <em>signature</em>.</dd>
<dt><sup>utils</sup> . verifyMessage ( messageStringOrArrayish , signature ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Addresss</sup></dt>
<dd>Returns the address of the account that signed <em>messageStringOrArrayish</em> to
generate <em>signature</em>.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id8">
<div class="code-block-caption"><span class="caption-text"><em>verify a message signature</em></span><a class="headerlink" href="#id8" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">signature</span> <span class="o">=</span> <span class="s2">&quot;0xddd0a7290af9526056b4e35a077b9a11b513aa0028ec6c9880948544508f3c63&quot;</span> <span class="o">+</span>
<span class="s2">&quot;265e99e47ad31bb2cab9646c504576b3abc6939a1710afc08cbf3034d73214b8&quot;</span> <span class="o">+</span>
<span class="s2">&quot;1c&quot;</span><span class="p">;</span>
<span class="kd">let</span> <span class="nx">signingAddress</span> <span class="o">=</span> <span class="nx">Wallet</span><span class="p">.</span><span class="nx">verifyMessage</span><span class="p">(</span><span class="s1">&#39;hello world&#39;</span><span class="p">,</span> <span class="nx">signature</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">signingAddress</span><span class="p">);</span>
<span class="c1">// &quot;0x14791697260E4c9A71f18484C9f997B308e59325&quot;</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="hash-functions">
<h3>Hash Functions<a class="headerlink" href="#hash-functions" title="Permalink to this headline"></a></h3>
<dl class="docutils">
<dt><sup>utils</sup> . keccak256 ( hexStringOrArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the keccak256 cryptographic hash of a value, returned as a hex string. (Note:
often Ethereum documentation refers to this, <strong>incorrectly</strong>, as SHA3)</dd>
<dt><sup>utils</sup> . sha256 ( hexStringOrArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the SHA2-256 cryptographic hash of a value, returned as a hex string.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id9">
<div class="code-block-caption"><span class="caption-text"><em>hashing binary data</em></span><a class="headerlink" href="#id9" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">keccak256</span><span class="p">([</span> <span class="mh">0x42</span> <span class="p">]));</span>
<span class="c1">// &#39;0x1f675bff07515f5df96737194ea945c36c41e7b4fcef307b7cd4d0e602a69111&#39;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">keccak256</span><span class="p">(</span><span class="s2">&quot;0x42&quot;</span><span class="p">));</span>
<span class="c1">// &#39;0x1f675bff07515f5df96737194ea945c36c41e7b4fcef307b7cd4d0e602a69111&#39;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">sha256</span><span class="p">([</span> <span class="mh">0x42</span> <span class="p">]));</span>
<span class="c1">// &#39;0xdf7e70e5021544f4834bbee64a9e3789febc4be81470df629cad6ddb03320a5c&#39;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">sha256</span><span class="p">(</span><span class="s2">&quot;0x42&quot;</span><span class="p">));</span>
<span class="c1">// &#39;0xdf7e70e5021544f4834bbee64a9e3789febc4be81470df629cad6ddb03320a5c&#39;</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="hash-function-helpers">
<h3>Hash Function Helpers<a class="headerlink" href="#hash-function-helpers" title="Permalink to this headline"></a></h3>
<dl class="docutils">
<dt><sup>utils</sup> . hashMessage ( stringOrArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the prefixed message hash of a stringOrArrayish, by converting the
message to bytes (as necessary) and prefixing with <code class="docutils literal notranslate"><span class="pre">\x19Ethereum</span> <span class="pre">Signed</span> <span class="pre">Message\n</span></code>
and the length of the message. See the <a class="reference external" href="https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign">eth_sign</a> JSON-RPC method for more information.</dd>
<dt><sup>utils</sup> . id ( utf8String ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the keccak256 cryptographic hash of a UTF-8 string, returned as a hex string.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id10">
<div class="code-block-caption"><span class="caption-text"><em>hashing utf-8 strings</em></span><a class="headerlink" href="#id10" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="c1">// Convert the string to binary data</span>
<span class="kd">let</span> <span class="nx">message</span> <span class="o">=</span> <span class="s2">&quot;Hello World&quot;</span><span class="p">;</span>
<span class="kd">let</span> <span class="nx">messageBytes</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">toUtf8Bytes</span><span class="p">(</span><span class="nx">message</span><span class="p">);</span>
<span class="nx">utils</span><span class="p">.</span><span class="nx">keccak256</span><span class="p">(</span><span class="nx">messageBytes</span><span class="p">);</span>
<span class="c1">// &#39;0x592fa743889fc7f92ac2a37bb1f5ba1daf2a5c84741ca0e0061d243a2e6707ba&#39;</span>
<span class="c1">// Which is equivalent to using the id function</span>
<span class="nx">utils</span><span class="p">.</span><span class="nx">id</span><span class="p">(</span><span class="s2">&quot;Hello World&quot;</span><span class="p">);</span>
<span class="c1">// &#39;0x592fa743889fc7f92ac2a37bb1f5ba1daf2a5c84741ca0e0061d243a2e6707ba&#39;</span>
<span class="c1">// Compute the sighash for a Solidity method</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">id</span><span class="p">(</span><span class="s2">&quot;addr(bytes32)&quot;</span><span class="p">));</span>
<span class="c1">// &#39;0x3b3b57de213591bb50e06975ea011e4c8c4b3e6de4009450c1a9e55f66e4bfa4&#39;</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="key-derivation">
<h3>Key Derivation<a class="headerlink" href="#key-derivation" title="Permalink to this headline"></a></h3>
<dl class="docutils">
<dt><sup>utils</sup> . pbkdf2 ( password , salt , iterations , keylen , hashAlgorithm )</dt>
<dd>Return the pbkdf2 derived key from <em>password</em> and <em>salt</em> with <em>iterations</em> of
<em>length</em> using the <em>hashAlgorithm</em>. The supported hash algorithms are <code class="docutils literal notranslate"><span class="pre">sha256</span></code>
and <code class="docutils literal notranslate"><span class="pre">sha512</span></code>.</dd>
</dl>
</div>
<div class="section" id="random">
<h3>Random<a class="headerlink" href="#random" title="Permalink to this headline"></a></h3>
<dl class="docutils">
<dt><sup>utils</sup> . randomBytes ( length ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Uint8Array</sup></dt>
<dd>Return a Uint8Array of cryptographically secure random bytes</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id11">
<div class="code-block-caption"><span class="caption-text"><em>generate random bytes</em></span><a class="headerlink" href="#id11" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">randomBytes3</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">randomBytes</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span>
<span class="c1">// Uint8Array [ 194, 22, 140 ]</span>
<span class="kd">let</span> <span class="nx">randomBytes32</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">randomBytes</span><span class="p">(</span><span class="mi">32</span><span class="p">)</span>
<span class="c1">// Uint8Array [ 162, 131, 117, 110, 196, 73, 144, 177, 201, 75, 88,</span>
<span class="c1">// 105, 227, 210, 104, 226, 82, 65, 103, 157, 36, 170,</span>
<span class="c1">// 214, 92, 190, 141, 239, 54, 96, 39, 240, 95 ]</span>
</pre></div>
</div>
</div>
<div class="literal-block-wrapper docutils container" id="id12">
<div class="code-block-caption"><span class="caption-text"><em>generate a random number</em></span><a class="headerlink" href="#id12" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">randomNumber</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">bigNumberify</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">randomBytes</span><span class="p">(</span><span class="mi">32</span><span class="p">));</span>
<span class="c1">// BigNumber { _hex: 0x617542634156966e0bbb6c673bf88015f542c96eb115186fd93881518f05f7ff }</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="solidity">
<h3>Solidity<a class="headerlink" href="#solidity" title="Permalink to this headline"></a></h3>
<p>Solidity uses a <a class="reference external" href="http://solidity.readthedocs.io/en/develop/abi-spec.html#non-standard-packed-mode">non-standard packed mode</a> to encode parameters that are passed
into its hashing functions. The parameter types and values can be used to compute
the result of the hash functions as would be performed by Solidity.</p>
<dl class="docutils">
<dt><sup>utils</sup> . solidityKeccak256 ( types, values ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the keccak256 cryptographic hash using the Solidity non-standard (tightly)
packed data for <em>values</em> given the <em>types</em>.</dd>
<dt><sup>utils</sup> . soliditySha256 ( types, values ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the SHA256 cryptographic hash using the Solidity non-standard (tightly)
packed data for <em>values</em> given the <em>types</em>.</dd>
<dt><sup>utils</sup> . solidityPack ( types, values ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the Solidity non-standard (tightly) packed data for <em>values</em> given the <em>types</em>.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id13">
<div class="code-block-caption"><span class="caption-text"><em>examples</em></span><a class="headerlink" href="#id13" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">result</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">solidityKeccak256</span><span class="p">([</span> <span class="s1">&#39;int8&#39;</span><span class="p">,</span> <span class="s1">&#39;bytes1&#39;</span><span class="p">,</span> <span class="s1">&#39;string&#39;</span> <span class="p">],</span> <span class="p">[</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="s1">&#39;0x42&#39;</span><span class="p">,</span> <span class="s1">&#39;hello&#39;</span> <span class="p">]);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">result</span><span class="p">);</span>
<span class="c1">// &#39;0x52d7e6a62ca667228365be2143375d0a2a92a3bd4325dd571609dfdc7026686e&#39;</span>
<span class="nx">result</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">soliditySha256</span><span class="p">([</span> <span class="s1">&#39;int8&#39;</span><span class="p">,</span> <span class="s1">&#39;bytes1&#39;</span><span class="p">,</span> <span class="s1">&#39;string&#39;</span> <span class="p">],</span> <span class="p">[</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="s1">&#39;0x42&#39;</span><span class="p">,</span> <span class="s1">&#39;hello&#39;</span> <span class="p">]);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">result</span><span class="p">);</span>
<span class="c1">// &#39;0x1eaebba7999af2691d823bf0c817e635bbe7e89ec7ed32a11e00ca94e86cbf37&#39;</span>
<span class="nx">result</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">solidityPack</span><span class="p">([</span> <span class="s1">&#39;int8&#39;</span><span class="p">,</span> <span class="s1">&#39;bytes1&#39;</span><span class="p">,</span> <span class="s1">&#39;string&#39;</span> <span class="p">],</span> <span class="p">[</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="s1">&#39;0x42&#39;</span><span class="p">,</span> <span class="s1">&#39;hello&#39;</span> <span class="p">]);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">result</span><span class="p">);</span>
<span class="c1">// &#39;0xff4268656c6c6f&#39;</span>
</pre></div>
</div>
</div>
</div>
</div>
<hr class="docutils" />
<div class="section" id="ether-strings-and-wei">
<h2>Ether Strings and Wei<a class="headerlink" href="#ether-strings-and-wei" title="Permalink to this headline"></a></h2>
<dl class="docutils">
<dt><sup>utils</sup> . etherSymbol</dt>
<dd>The ethereum symbol (the Greek letter <em>Xi</em> )</dd>
</dl>
<dl class="docutils" id="parseether">
<dt><sup>utils</sup> . parseEther ( etherString ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Parse the <em>etherString</em> representation of ether into a BigNumber instance
of the amount of wei.</dd>
</dl>
<dl class="docutils" id="formatether">
<dt><sup>utils</sup> . formatEther ( wei ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>string</sup></dt>
<dd>Format an amount of <em>wei</em> into a decimal string representing the amount of ether.
The output will always include at least one whole number and at least one decimal
place, otherwise leading and trailing 0s will be trimmed.</dd>
</dl>
<dl class="docutils" id="parseunits">
<dt><sup>utils</sup> . parseUnits ( valueString , decimalsOrUnitName ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>BigNumber</sup></dt>
<dd>Parse the <em>valueString</em> representation of units into a BigNumber instance
of the amount of wei. The <em>decimalsOrUnitsName</em> may be a number of decimals between
3 and 18 (multiple of 3) or a name, such as <cite>gwei</cite>.</dd>
</dl>
<dl class="docutils" id="formatunits">
<dt><sup>utils</sup> . formatUnits ( wei , decimalsOrUnitName ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>string</sup></dt>
<dd>Format an amount of <em>wei</em> into a decimal string representing the amount of units.
The output will always include at least one whole number and at least one decimal place,
otherwise leading and trailing 0s will be trimmed. The <em>decimalsOrUnitsName</em>
may be a number of decimals between 3 and 18 (multiple of 3) or a name, such as <cite>gwei</cite>.</dd>
<dt><sup>utils</sup> . commify ( numberOrString ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>string</sup></dt>
<dd>Returns <em>numberOrString</em> with commas placed at every third position within the whole
component. If <em>numberOrString</em> contains a decimal point, the output will as well with
at least one digit for both the whole and decimal components. If there no decimal,
then the output will also not contain a decimal.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id14">
<div class="code-block-caption"><span class="caption-text"><em>examples</em></span><a class="headerlink" href="#id14" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">wei</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">parseEther</span><span class="p">(</span><span class="s1">&#39;1000.0&#39;</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">wei</span><span class="p">.</span><span class="nx">toString</span><span class="p">(</span><span class="mi">10</span><span class="p">));</span>
<span class="c1">// &quot;1000000000000000000000&quot;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">formatEther</span><span class="p">(</span><span class="mi">0</span><span class="p">));</span>
<span class="c1">// &quot;0.0&quot;</span>
<span class="kd">let</span> <span class="nx">wei</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">bigNumberify</span><span class="p">(</span><span class="s2">&quot;1000000000000000000000&quot;</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">formatEther</span><span class="p">(</span><span class="nx">wei</span><span class="p">));</span>
<span class="c1">// &quot;1000.0&quot;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">formatEther</span><span class="p">(</span><span class="nx">wei</span><span class="p">,</span> <span class="p">{</span><span class="nx">commify</span><span class="o">:</span> <span class="kc">true</span><span class="p">}));</span>
<span class="c1">// &quot;1,000.0&quot;</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">formatEther</span><span class="p">(</span><span class="nx">wei</span><span class="p">,</span> <span class="p">{</span><span class="nx">pad</span><span class="o">:</span> <span class="kc">true</span><span class="p">}));</span>
<span class="c1">// &quot;1000.000000000000000000&quot; (18 decimal places)</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">utils</span><span class="p">.</span><span class="nx">formatEther</span><span class="p">(</span><span class="nx">wei</span><span class="p">,</span> <span class="p">{</span><span class="nx">commify</span><span class="o">:</span> <span class="kc">true</span><span class="p">,</span> <span class="nx">pad</span><span class="o">:</span> <span class="kc">true</span><span class="p">}));</span>
<span class="c1">// &quot;1,000.000000000000000000&quot; (18 decimal places)</span>
</pre></div>
</div>
</div>
<hr class="docutils" />
</div>
<div class="section" id="hex-strings">
<span id="hexstring"></span><h2>Hex Strings<a class="headerlink" href="#hex-strings" title="Permalink to this headline"></a></h2>
<p>A hex string is <strong>always</strong> prefixed with “0x” and consists of the characters
0 9 and a f. It is always returned lower case with even-length, but any hex
string passed into a function may be any case and may be odd-length.</p>
<dl class="docutils">
<dt><sup>utils</sup> . hexlify ( numberOrBigNumberOrHexStringOrArrayish ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Converts any number, <a class="reference internal" href="#bignumber"><span class="std std-ref">BigNumber</span></a>, hex string or
<a class="reference internal" href="#arrayish">Arrayish</a> to a hex string. (otherwise, throws an error)</dd>
<dt><sup>utils</sup> . isHexString ( value ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>boolean</sup></dt>
<dd>Returns true if <em>value</em> is a valid hexstring.</dd>
<dt><sup>utils</sup> . hexDataLength ( hexString ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>number</sup></dt>
<dd>Returns the length (in bytes) of <em>hexString</em> if it is a valid data hexstring (even length).</dd>
<dt><sup>utils</sup> . hexDataSlice ( hexString , offset [ , endOffset ] ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Returns a string for the subdata of <em>hexString</em> from <em>offset</em> <strong>bytes</strong>
(each byte is two nibbled) to <em>endOffset</em> <strong>bytes</strong>. If no <em>endOffset</em> is
specified, the result is to the end of the <em>hexString</em> is used. Each byte is two nibbles.</dd>
<dt><sup>utils</sup> . hexStripZeros ( hexString ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Returns <em>hexString</em> with all leading zeros removed, but retaining at least
one nibble, even if zero (e.g. <code class="docutils literal notranslate"><span class="pre">0x0</span></code>). This may return an odd-length string.</dd>
<dt><sup>utils</sup> . hexZeroPad ( hexString , length ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Returns <em>hexString</em> padded (on the left) with zeros to length <strong>bytes</strong> (each
byte is two nibbles).</dd>
</dl>
</div>
<hr class="docutils" />
<div class="section" id="namehash">
<h2>Namehash<a class="headerlink" href="#namehash" title="Permalink to this headline"></a></h2>
<dl class="docutils">
<dt><sup>utils</sup> . namehash ( ensName ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Compute the namehash of <em>ensName</em>. Currently only supports the
characters <code class="docutils literal notranslate"><span class="pre">[a-z0-9.-]</span></code>. The concerns with fully supporting UTF-8
are largely security releated, but <a class="reference external" href="https://github.com/ethers-io/ethers.js/issues/42">are open for discussion</a>.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id15">
<div class="code-block-caption"><span class="caption-text"><em>examples</em></span><a class="headerlink" href="#id15" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">namehash</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">namehash</span><span class="p">(</span><span class="s1">&#39;ricmoo.firefly.eth&#39;</span><span class="p">);</span>
<span class="c1">// &quot;0x0bcad17ecf260d6506c6b97768bdc2acfb6694445d27ffd3f9c1cfbee4a9bd6d&quot;</span>
</pre></div>
</div>
</div>
<hr class="docutils" />
</div>
<div class="section" id="signatures">
<span id="signature"></span><h2>Signatures<a class="headerlink" href="#signatures" title="Permalink to this headline"></a></h2>
<p>There are two common formats for signatures in Ethereum. The <strong>flat-format</strong>, which
is a hexstring with 65 bytes (130 nibbles); or an <strong>expanded-format</strong>, which is an object with
the properties:</p>
<blockquote>
<div><ul class="simple">
<li><strong>r</strong> and <strong>s</strong> — the (r, s) public point of a signature</li>
<li><strong>recoveryParam</strong> — the recovery parameter of a signautre (either <code class="docutils literal notranslate"><span class="pre">0</span></code> or <code class="docutils literal notranslate"><span class="pre">1</span></code>)</li>
<li><strong>v</strong> — the recovery param nomalized for Solidity (either <code class="docutils literal notranslate"><span class="pre">27</span></code> or <code class="docutils literal notranslate"><span class="pre">28</span></code>)</li>
</ul>
</div></blockquote>
<dl class="docutils">
<dt><sup>utils</sup> . splitSignature ( hexStringOrArrayishOrSignature ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Signature</sup></dt>
<dd>Returns an expanded-format signature object for <em>hexStringOrArrayishOrSignature</em>.
Passing in an signature that is already in the expanded-format will ensure
both <em>recoveryParam</em> and <em>v</em> are populated.</dd>
<dt><sup>utils</sup> . joinSignature ( signature ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd>Returns the flat-format signature hexstring of <em>signature</em>. The final <em>v</em>
byte will always be normalized to <code class="docutils literal notranslate"><span class="pre">0x1b</span></code> of <code class="docutils literal notranslate"><span class="pre">0x1c</span></code>.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id16">
<div class="code-block-caption"><span class="caption-text"><em>To Expanded-Format</em></span><a class="headerlink" href="#id16" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="c1">// Flat-format; this is the format provided by JSON-RPC responses</span>
<span class="kd">let</span> <span class="nx">flat</span> <span class="o">=</span> <span class="s2">&quot;0x0ba9770fd8778383f6d56faadc71e17b75f0d6e3ff0a408d5e6c4cee3bd70a16&quot;</span> <span class="o">+</span>
<span class="s2">&quot;3574da0ebfb1eaac261698b057b342e52ea53f85287272cea471a4cda41e3466&quot;</span> <span class="o">+</span>
<span class="s2">&quot;1b&quot;</span>
<span class="kd">let</span> <span class="nx">expanded</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">splitSignature</span><span class="p">(</span><span class="nx">flat</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">expanded</span><span class="p">);</span>
<span class="c1">// {</span>
<span class="c1">// r: &quot;0x0ba9770fd8778383f6d56faadc71e17b75f0d6e3ff0a408d5e6c4cee3bd70a16&quot;,</span>
<span class="c1">// s: &quot;0x3574da0ebfb1eaac261698b057b342e52ea53f85287272cea471a4cda41e3466&quot;,</span>
<span class="c1">// recoveryParam: 0,</span>
<span class="c1">// v: 27</span>
<span class="c1">// }</span>
</pre></div>
</div>
</div>
<div class="literal-block-wrapper docutils container" id="id17">
<div class="code-block-caption"><span class="caption-text"><em>To Flat-Format</em></span><a class="headerlink" href="#id17" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="c1">// Expanded-format; this is the format Solidity and other tools often require</span>
<span class="kd">let</span> <span class="nx">expanded</span> <span class="o">=</span> <span class="p">{</span>
<span class="nx">r</span><span class="o">:</span> <span class="s2">&quot;0x0ba9770fd8778383f6d56faadc71e17b75f0d6e3ff0a408d5e6c4cee3bd70a16&quot;</span><span class="p">,</span>
<span class="nx">s</span><span class="o">:</span> <span class="s2">&quot;0x3574da0ebfb1eaac261698b057b342e52ea53f85287272cea471a4cda41e3466&quot;</span><span class="p">,</span>
<span class="nx">recoveryParam</span><span class="o">:</span> <span class="mi">0</span><span class="p">,</span>
<span class="nx">v</span><span class="o">:</span> <span class="mi">27</span>
<span class="p">}</span>
<span class="kd">let</span> <span class="nx">flat</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">joinSignature</span><span class="p">(</span><span class="nx">expanded</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">flat</span><span class="p">)</span>
<span class="c1">// &quot;0x0ba9770fd8778383f6d56faadc71e17b75f0d6e3ff0a408d5e6c4cee3bd70a16&quot; +</span>
<span class="c1">// &quot;3574da0ebfb1eaac261698b057b342e52ea53f85287272cea471a4cda41e3466&quot; +</span>
<span class="c1">// &quot;1b&quot;</span>
</pre></div>
</div>
</div>
<hr class="docutils" />
</div>
<div class="section" id="transactions">
<span id="id3"></span><h2>Transactions<a class="headerlink" href="#transactions" title="Permalink to this headline"></a></h2>
<dl class="docutils">
<dt><sup>utils</sup> . serializeTransaction ( transaction [ , signature ] ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>hex</sup></dt>
<dd><p class="first">Serialize <em>transaction</em> as a <a class="reference internal" href="#hexstring"><span class="std std-ref">hex-string</span></a>, optionally including
the <em>signature</em>.</p>
<p class="last">If <em>signature</em> is provided, it may be either the <a class="reference internal" href="#signature"><span class="std std-ref">Flat Format</span></a>
or the <a class="reference internal" href="#signature"><span class="std std-ref">Expanded Format</span></a>, and the serialized transaction will
be a signed transaction.</p>
</dd>
<dt><sup>utils</sup> . parseTransaction ( rawTransaction ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Transaction</sup></dt>
<dd><p class="first">Parse the serialized transaction, returning an object with the properties:</p>
<blockquote>
<div><ul class="simple">
<li><strong>to</strong></li>
<li><strong>nonce</strong></li>
<li><strong>gasPrice</strong></li>
<li><strong>gasLimit</strong></li>
<li><strong>data</strong></li>
<li><strong>value</strong></li>
<li><strong>chainId</strong></li>
</ul>
</div></blockquote>
<p>If the transactions is signed, addition properties will be present:</p>
<blockquote class="last">
<div><ul class="simple">
<li><strong>r</strong>, <strong>s</strong> and <strong>v</strong> — the signature public point and recoveryParam (adjusted for the chainId)</li>
<li><strong>from</strong> — the address of the account that signed the transaction</li>
<li><strong>hash</strong> — the transaction hash</li>
</ul>
</div></blockquote>
</dd>
</dl>
<hr class="docutils" />
</div>
<div class="section" id="utf-8-strings">
<span id="utf8-strings"></span><h2>UTF-8 Strings<a class="headerlink" href="#utf-8-strings" title="Permalink to this headline"></a></h2>
<dl class="docutils" id="utf8-to-bytes">
<dt><sup>utils</sup> . toUtf8Bytes ( string ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Uint8Array</sup></dt>
<dd>Converts a UTF-8 string to a Uint8Array.</dd>
</dl>
<dl class="docutils" id="utf8-to-string">
<dt><sup>utils</sup> . toUtf8String ( hexStringOrArrayish , [ ignoreErrors <sup>= false</sup> ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>string</sup></dt>
<dd>Converts a hex-encoded string or array to its UTF-8 representation.</dd>
</dl>
<div class="literal-block-wrapper docutils container" id="id18">
<div class="code-block-caption"><span class="caption-text"><em>To UTF-8 Bytes</em></span><a class="headerlink" href="#id18" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">text</span> <span class="o">=</span> <span class="s2">&quot;Hello World&quot;</span><span class="p">;</span>
<span class="kd">let</span> <span class="nx">bytes</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">toUtf8Bytes</span><span class="p">(</span><span class="nx">text</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">bytes</span><span class="p">);</span>
<span class="c1">// Uint8Array [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]</span>
</pre></div>
</div>
</div>
<div class="literal-block-wrapper docutils container" id="id19">
<div class="code-block-caption"><span class="caption-text"><em>To UTF-8 String</em></span><a class="headerlink" href="#id19" title="Permalink to this code"></a></div>
<div class="highlight-javascript notranslate"><div class="highlight"><pre><span></span><span class="kd">let</span> <span class="nx">array</span> <span class="o">=</span> <span class="p">[</span><span class="mi">72</span><span class="p">,</span> <span class="mi">101</span><span class="p">,</span> <span class="mi">108</span><span class="p">,</span> <span class="mi">108</span><span class="p">,</span> <span class="mi">111</span><span class="p">,</span> <span class="mi">32</span><span class="p">,</span> <span class="mi">87</span><span class="p">,</span> <span class="mi">111</span><span class="p">,</span> <span class="mi">114</span><span class="p">,</span> <span class="mi">108</span><span class="p">,</span> <span class="mi">100</span><span class="p">];</span>
<span class="kd">let</span> <span class="nx">stringFromArray</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">toUtf8String</span><span class="p">(</span><span class="nx">array</span><span class="p">)</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">stringFromArray</span><span class="p">);</span>
<span class="c1">// &quot;Hello World&quot;</span>
<span class="kd">let</span> <span class="nx">hexString</span> <span class="o">=</span> <span class="s2">&quot;0x48656c6c6f20576f726c64&quot;</span><span class="p">;</span>
<span class="kd">let</span> <span class="nx">stringFromHexString</span> <span class="o">=</span> <span class="nx">utils</span><span class="p">.</span><span class="nx">toUtf8String</span><span class="p">(</span><span class="nx">hexString</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">stringFromHexString</span><span class="p">);</span>
<span class="c1">// &quot;Hello World&quot;</span>
</pre></div>
</div>
</div>
</div>
<hr class="docutils" />
<div class="section" id="web">
<h2>Web<a class="headerlink" href="#web" title="Permalink to this headline"></a></h2>
<dl class="docutils">
<dt><sup>utils</sup> . fetchJson ( urlOrInfo [ , processFunc ] ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Promise&lt;any&gt;</sup></dt>
<dd><p class="first">Returns a <a class="reference internal" href="notes.html#promise"><span class="std std-ref">Promise</span></a> of the contents of <em>urlOrInfo</em>, processed by
<em>processFunc</em>.</p>
<p>The <em>urlOrInfo</em> may also be specified as an object with the properties:</p>
<blockquote class="last">
<div><ul class="simple">
<li><strong>url</strong> — the JSON-RPC URL (required)</li>
<li><strong>user</strong> — a username to use for Basic Authentication (optional)</li>
<li><strong>password</strong> — a password to use for Basic Authentication (optional)</li>
<li><strong>allowInsecure</strong> — allow Basic Authentication over an insecure HTTP network (default: false)</li>
<li><strong>timeout</strong> — number of milliseconds to abort the request (default: 2 minutes)</li>
<li><strong>headers</strong> — additional headers to send to the server (case insensitive)</li>
</ul>
</div></blockquote>
</dd>
<dt><sup>utils</sup> . poll ( func , [ options ] ) &nbsp; <sup>=&gt;</sup> &nbsp; <sup>Promise&lt;any&gt;</sup></dt>
<dd><p class="first">Poll using the function <em>func</em>, resolving when it does not return <code class="docutils literal notranslate"><span class="pre">undefined</span></code>. By
default this method will use the <a class="reference external" href="https://en.wikipedia.org/wiki/Exponential_backoff">exponential back-off</a> algorithm.</p>
<p>The <em>options</em> is an object with the properties:</p>
<blockquote class="last">
<div><ul class="simple">
<li><strong>timeout</strong> — after this many millisecconds, the promise will reject with a <code class="docutils literal notranslate"><span class="pre">timeout</span></code> error (default: no timeout)</li>
<li><strong>floor</strong> — minimum amount of time between polling (default: 0)</li>
<li><strong>ceiling</strong> — minimum amount of time between polling (default: 10s)</li>
<li><strong>interval</strong> — the interval to use for exponential backoff (default: 250ms)</li>
<li><strong>onceBlock</strong> — a function which takes 2 parameters, the string <code class="docutils literal notranslate"><span class="pre">block</span></code> and a callback <em>func</em>; polling will occur everytime <em>func</em> is called; any provider can be passed in for this property</li>
</ul>
</div></blockquote>
</dd>
</dl>
<hr class="docutils" />
</div>
</div>
</div>
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