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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 exposed in both the <em>ethers</em> umbrella package and the <em>ethers-utils</em>:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
</pre></div>
</div>
<hr class="docutils" />
<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 math operations to be carried
out on numbers far larger than <a class="reference internal" href="notes.html#ieee754"><span class="std std-ref">JavaScript can accurately handle</span></a>.
Many functions return these, so it is important to understand how to work with these.</p>
<dl class="docutils">
<dt><sup>prototype</sup> . add ( otherValue )</dt>
<dd>Return a new BigNumber of this plus <em>otherValue</em></dd>
<dt><sup>prototype</sup> . sub ( otherValue )</dt>
<dd>Return a new BigNumber of this minus <em>otherValue</em></dd>
<dt><sup>prototype</sup> . mul ( otherValue )</dt>
<dd>Return a new BigNumber of this times <em>otherValue</em></dd>
<dt><sup>prototype</sup> . div ( otherValue )</dt>
<dd>Return a new BigNumber of this divided by <em>otherValue</em></dd>
<dt><sup>prototype</sup> . mod ( otherValue )</dt>
<dd>Return a new BigNumber of this modulo <em>otherValue</em></dd>
<dt><sup>prototype</sup> . eq ( otherValue )</dt>
<dd>Return true if this is equal to <em>otherValue</em></dd>
<dt><sup>prototype</sup> . lt ( otherValue )</dt>
<dd>Return true if this is less than <em>otherValue</em></dd>
<dt><sup>prototype</sup> . lte ( otherValue )</dt>
<dd>Return true if this is less or equal to <em>otherValue</em></dd>
<dt><sup>prototype</sup> . gt ( otherValue )</dt>
<dd>Return true if this is greater than <em>otherValue</em></dd>
<dt><sup>prototype</sup> . gte ( otherValue )</dt>
<dd>Return true if this is greater than or equal to <em>otherValue</em></dd>
<dt><sup>prototype</sup> . isZero ( )</dt>
<dd>Return true if this is equal to zero</dd>
<dt><sup>prototype</sup> . toNumber ( )</dt>
<dd>Return a JavaScript number representation; an error is thrown if the value is
outside the safe range for JavaScript IEEE 754 64-bit floating point numbers</dd>
<dt><sup>prototype</sup> . toString ()</dt>
<dd>Return a decimal string representation</dd>
<dt><sup>prototype</sup> . toHexString ( )</dt>
<dd>Return a <strong>0x prefixed</strong> hexidecimal representation</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> <strong>. bigNumberify</strong> ( value )</dt>
<dd><p class="first">Returns a BigNumber instance of <em>value</em>. The <em>value</em> may be anything which can be
reliably converted into a BigNumber:</p>
<dl class="last docutils">
<dt><em>Decimal String</em></dt>
<dd><p class="first">A string consisting of the decimal digits 0 through 9, optionally with a leading
negative sign.</p>
<p class="last"><strong>examples:</strong> utils.bigNumberify(“42”)</p>
</dd>
<dt><em>Hex String</em></dt>
<dd><p class="first">A <a class="reference internal" href="#hexstring"><span class="std std-ref">hex string</span></a>, witch has aa <strong>prefix of 0x</strong> and consisting
of the hexidecimal digits 0 through 9 and a through f, case-insensitive. Must
be non-negative.</p>
<p class="last"><strong>examples:</strong> utils.bigNumberify(“0x2a”)</p>
</dd>
<dt><em>JavaScript Numbers</em></dt>
<dd><p class="first">Numbers must be within the <a class="reference external" href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger">safe range</a> for JavaScript.</p>
<p class="last"><strong>examples:</strong> utils.bigNumberify(42)</p>
</dd>
<dt><em>Arrayish</em></dt>
<dd><p class="first">Treats the <a class="reference internal" href="#api-arrayish"><span class="std std-ref">arrayish</span></a> as a big-endian encoded bytes representation.</p>
<p class="last"><strong>examples:</strong> utils.bigNumberify([ 42 ])</p>
</dd>
<dt><em>BigNumber</em></dt>
<dd>Returns <em>value</em>, since a BigNumber is immutable.</dd>
</dl>
</dd>
</dl>
</div>
<div class="section" id="examples">
<h3><em>Examples</em><a class="headerlink" href="#examples" title="Permalink to this headline"></a></h3>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="n">var</span> <span class="n">gasPriceWei</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">bigNumberify</span><span class="p">(</span><span class="s2">&quot;20902747399&quot;</span><span class="p">);</span>
<span class="n">var</span> <span class="n">gasLimit</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">bigNumberify</span><span class="p">(</span><span class="mi">3000000</span><span class="p">);</span>
<span class="n">var</span> <span class="n">maxCostWei</span> <span class="o">=</span> <span class="n">gasPriceWei</span><span class="o">.</span><span class="n">mul</span><span class="p">(</span><span class="n">gasLimit</span><span class="p">)</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="s2">&quot;Max Cost: &quot;</span> <span class="o">+</span> <span class="n">maxCostWei</span><span class="o">.</span><span class="n">toString</span><span class="p">());</span>
<span class="o">//</span> <span class="s2">&quot;Max Cost: 62708242197000000&quot;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="s2">&quot;Number: &quot;</span> <span class="o">+</span> <span class="n">maxCostWei</span><span class="o">.</span><span class="n">toNumber</span><span class="p">());</span>
<span class="o">//</span> <span class="n">throws</span> <span class="n">an</span> <span class="n">Error</span><span class="p">,</span> <span class="n">the</span> <span class="n">value</span> <span class="ow">is</span> <span class="n">too</span> <span class="n">large</span> <span class="k">for</span> <span class="n">JavaScript</span> <span class="n">to</span> <span class="n">handle</span> <span class="n">safely</span>
</pre></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 )</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 [ , options ] )</dt>
<dd>Format an amount of <em>wei</em> into a decimal string representing the amount of ether. The
<em>options</em> object supports the keys <code class="docutils literal"><span class="pre">commify</span></code> and <code class="docutils literal"><span class="pre">pad</span></code>. The output will always
include at least one whole number and at least one decimal place.</dd>
</dl>
<dl class="docutils" id="parseunits">
<dt><sup>utils</sup> . parseUnits ( valueString , decimalsOrUnitName )</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 [ , options ] )</dt>
<dd>Format an amount of <em>wei</em> into a decimal string representing the amount of units. The
<em>options</em> object supports the keys <code class="docutils literal"><span class="pre">commify</span></code> and <code class="docutils literal"><span class="pre">pad</span></code>. The output will always
include at least one whole number and at least one decimal place. 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>
<div class="section" id="id1">
<h3><em>Examples</em><a class="headerlink" href="#id1" title="Permalink to this headline"></a></h3>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="n">var</span> <span class="n">wei</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">parseEther</span><span class="p">(</span><span class="s1">&#39;1000.0&#39;</span><span class="p">);</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">wei</span><span class="o">.</span><span class="n">toString</span><span class="p">(</span><span class="mi">10</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;1000000000000000000000&quot;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">formatEther</span><span class="p">(</span><span class="mi">0</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;0.0&quot;</span>
<span class="n">var</span> <span class="n">wei</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">bigNumberify</span><span class="p">(</span><span class="s2">&quot;1000000000000000000000&quot;</span><span class="p">);</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">formatEther</span><span class="p">(</span><span class="n">wei</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;1000.0&quot;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">formatEther</span><span class="p">(</span><span class="n">wei</span><span class="p">,</span> <span class="p">{</span><span class="n">commify</span><span class="p">:</span> <span class="n">true</span><span class="p">}));</span>
<span class="o">//</span> <span class="s2">&quot;1,000.0&quot;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">formatEther</span><span class="p">(</span><span class="n">wei</span><span class="p">,</span> <span class="p">{</span><span class="n">pad</span><span class="p">:</span> <span class="n">true</span><span class="p">}));</span>
<span class="o">//</span> <span class="s2">&quot;1000.000000000000000000&quot;</span> <span class="p">(</span><span class="mi">18</span> <span class="n">decimal</span> <span class="n">places</span><span class="p">)</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">formatEther</span><span class="p">(</span><span class="n">wei</span><span class="p">,</span> <span class="p">{</span><span class="n">commify</span><span class="p">:</span> <span class="n">true</span><span class="p">,</span> <span class="n">pad</span><span class="p">:</span> <span class="n">true</span><span class="p">}));</span>
<span class="o">//</span> <span class="s2">&quot;1,000.000000000000000000&quot;</span> <span class="p">(</span><span class="mi">18</span> <span class="n">decimal</span> <span class="n">places</span><span class="p">)</span>
</pre></div>
</div>
</div>
</div>
<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 on the Ethereum network for
addresses, and it is often useful to be able to convert between them.</p>
<dl class="docutils" id="api-getaddress">
<dt><sup>utils</sup> . getAddress ( address [ , generateIcap ] )</dt>
<dd>Normalize an address to a <a class="reference internal" href="notes.html#checksum-address"><span class="std std-ref">checksum address</span></a>, or as an
<a class="reference internal" href="notes.html#icap-address"><span class="std std-ref">ICAP</span></a> address if <em>generateIcap</em> is true.</dd>
</dl>
<div class="section" id="id2">
<h3><em>Examples</em><a class="headerlink" href="#id2" title="Permalink to this headline"></a></h3>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="n">var</span> <span class="n">address</span> <span class="o">=</span> <span class="s2">&quot;0xd115bffabbdd893a6f7cea402e7338643ced44a6&quot;</span><span class="p">;</span>
<span class="n">var</span> <span class="n">icapAddress</span> <span class="o">=</span> <span class="s2">&quot;XE93OF8SR0OWI6F4FO88KWO4UNNGG1FEBHI&quot;</span><span class="p">;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">getAddress</span><span class="p">(</span><span class="n">address</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;0xD115BFFAbbdd893A6f7ceA402e7338643Ced44a6&quot;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">getAddress</span><span class="p">(</span><span class="n">icapAddress</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;0xD115BFFAbbdd893A6f7ceA402e7338643Ced44a6&quot;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">getAddress</span><span class="p">(</span><span class="n">address</span><span class="p">,</span> <span class="n">true</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;XE93OF8SR0OWI6F4FO88KWO4UNNGG1FEBHI&quot;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">getAddress</span><span class="p">(</span><span class="n">icapAddress</span><span class="p">,</span> <span class="n">true</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;XE93OF8SR0OWI6F4FO88KWO4UNNGG1FEBHI&quot;</span>
</pre></div>
</div>
<hr class="docutils" />
</div>
</div>
<div class="section" id="utf-8-strings">
<span id="api-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="api-utf8-to-bytes">
<dt><sup>utils</sup> . toUtf8Bytes ( string )</dt>
<dd>Converts a UTF-8 string to a Uint8Array.</dd>
</dl>
<dl class="docutils" id="api-utf8-to-string">
<dt><sup>utils</sup> . toUtf8String ( hexStringOrArrayish )</dt>
<dd>Converts a hex-encoded string or array to its UTF-8 representation.</dd>
</dl>
<div class="section" id="id3">
<h3><em>Examples</em><a class="headerlink" href="#id3" title="Permalink to this headline"></a></h3>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="n">var</span> <span class="n">text</span> <span class="o">=</span> <span class="s2">&quot;Hello World&quot;</span><span class="p">;</span>
<span class="n">var</span> <span class="nb">bytes</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">toUtf8Bytes</span><span class="p">(</span><span class="n">text</span><span class="p">);</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="nb">bytes</span><span class="p">);</span>
<span class="o">//</span> <span class="n">Uint8Array</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="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">toUtf8String</span><span class="p">(</span><span class="nb">bytes</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;Hello World&quot;</span>
<span class="n">var</span> <span class="n">hexString</span> <span class="o">=</span> <span class="s2">&quot;0x48656c6c6f20576f726c64&quot;</span><span class="p">;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">toUtf8String</span><span class="p">(</span><span class="n">hexString</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;Hello World&quot;</span>
</pre></div>
</div>
<hr class="docutils" />
</div>
</div>
<div class="section" id="cryptographic-functions">
<span id="api-utils-crypto"></span><h2>Cryptographic Functions<a class="headerlink" href="#cryptographic-functions" title="Permalink to this headline"></a></h2>
<dl class="docutils">
<dt><sup>utils</sup> . keccak256 ( hexStringOrArrayish )</dt>
<dd>Compute the keccak256 cryptographic hash of a value, returned as a hex string. (Note:
often Ethereum refers to this, <strong>incorrectly</strong>, as SHA3)</dd>
<dt><sup>utils</sup> . id ( utf8String )</dt>
<dd>Compute the keccak256 cryptographic hash of a UTF-8 string, returned as a hex string.</dd>
<dt><sup>utils</sup> . sha256 ( hexStringOrArrayish )</dt>
<dd>Compute the SHA2-256 cryptographic hash of a value, returned as a hex string.</dd>
<dt><sup>utils</sup> . randomBytes ( length )</dt>
<dd>Return a Uint8Array of cryptographically secure random bytes</dd>
</dl>
<div class="section" id="id4">
<h3><em>Examples</em><a class="headerlink" href="#id4" title="Permalink to this headline"></a></h3>
<p><strong>Hashing Binary Data</strong></p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">keccak256</span><span class="p">([</span> <span class="mh">0x42</span> <span class="p">]));</span>
<span class="o">//</span> <span class="s1">&#39;0x1f675bff07515f5df96737194ea945c36c41e7b4fcef307b7cd4d0e602a69111&#39;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">keccak256</span><span class="p">(</span><span class="s2">&quot;0x42&quot;</span><span class="p">));</span>
<span class="o">//</span> <span class="s1">&#39;0x1f675bff07515f5df96737194ea945c36c41e7b4fcef307b7cd4d0e602a69111&#39;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">sha256</span><span class="p">([</span> <span class="mh">0x42</span> <span class="p">]));</span>
<span class="o">//</span> <span class="s1">&#39;0xdf7e70e5021544f4834bbee64a9e3789febc4be81470df629cad6ddb03320a5c&#39;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">sha256</span><span class="p">(</span><span class="s2">&quot;0x42&quot;</span><span class="p">));</span>
<span class="o">//</span> <span class="s1">&#39;0xdf7e70e5021544f4834bbee64a9e3789febc4be81470df629cad6ddb03320a5c&#39;</span>
</pre></div>
</div>
<p><strong>Hashing UTF-8 Strings</strong></p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="o">//</span> <span class="n">Convert</span> <span class="n">the</span> <span class="n">string</span> <span class="n">to</span> <span class="n">binary</span> <span class="n">data</span>
<span class="n">var</span> <span class="n">utf8Bytes</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">toUtf8Bytes</span><span class="p">(</span><span class="s1">&#39;Hello World&#39;</span><span class="p">);</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">keccak256</span><span class="p">(</span><span class="n">utf8Bytes</span><span class="p">));</span>
<span class="o">//</span> <span class="s1">&#39;0x592fa743889fc7f92ac2a37bb1f5ba1daf2a5c84741ca0e0061d243a2e6707ba&#39;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">sha256</span><span class="p">(</span><span class="n">utf8Bytes</span><span class="p">));</span>
<span class="o">//</span> <span class="s1">&#39;0xa591a6d40bf420404a011733cfb7b190d62c65bf0bcda32b57b277d9ad9f146e&#39;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">id</span><span class="p">(</span><span class="s2">&quot;Hello World&quot;</span><span class="p">));</span>
<span class="o">//</span> <span class="s1">&#39;0x592fa743889fc7f92ac2a37bb1f5ba1daf2a5c84741ca0e0061d243a2e6707ba&#39;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">id</span><span class="p">(</span><span class="s2">&quot;addr(bytes32)&quot;</span><span class="p">));</span>
<span class="o">//</span> <span class="s1">&#39;0x3b3b57de213591bb50e06975ea011e4c8c4b3e6de4009450c1a9e55f66e4bfa4&#39;</span>
</pre></div>
</div>
<p><strong>Random Bytes</strong></p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">randomBytes</span><span class="p">(</span><span class="mi">3</span><span class="p">));</span>
<span class="o">//</span> <span class="n">Uint8Array</span> <span class="p">[</span> <span class="mi">194</span><span class="p">,</span> <span class="mi">22</span><span class="p">,</span> <span class="mi">140</span> <span class="p">]</span>
</pre></div>
</div>
</div>
</div>
<hr class="docutils" />
<div class="section" id="solidity-cryptographic-functions">
<h2>Solidity Cryptographic Functions<a class="headerlink" href="#solidity-cryptographic-functions" title="Permalink to this headline"></a></h2>
<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 )</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 )</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 )</dt>
<dd>Compute the Solidity non-standard (tightly) packed data for <em>values</em> given the <em>types</em>.</dd>
</dl>
<div class="section" id="id5">
<h3><em>Examples</em><a class="headerlink" href="#id5" title="Permalink to this headline"></a></h3>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="n">var</span> <span class="n">result</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">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="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">result</span><span class="p">);</span>
<span class="o">//</span> <span class="s1">&#39;0x52d7e6a62ca667228365be2143375d0a2a92a3bd4325dd571609dfdc7026686e&#39;</span>
<span class="n">result</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">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="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">result</span><span class="p">);</span>
<span class="o">//</span> <span class="s1">&#39;0x1eaebba7999af2691d823bf0c817e635bbe7e89ec7ed32a11e00ca94e86cbf37&#39;</span>
<span class="n">result</span> <span class="o">=</span> <span class="n">utils</span><span class="o">.</span><span class="n">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="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">result</span><span class="p">);</span>
<span class="o">//</span> <span class="s1">&#39;0xff4268656c6c6f&#39;</span>
</pre></div>
</div>
<hr class="docutils" />
</div>
</div>
<div class="section" id="arrayish">
<span id="api-arrayish"></span><h2>Arrayish<a class="headerlink" href="#arrayish" title="Permalink to this headline"></a></h2>
<p>An arrayish object is any such that it:</p>
<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>
<dl class="docutils">
<dt><sup>utils</sup> . isArrayish ( object )</dt>
<dd>Returns true if <em>object</em> can be treated as an arrayish object.</dd>
<dt><sup>utils</sup> . arrayify ( hexStringOrBigNumberOrArrayish )</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 )</dt>
<dd>Return a Uint8Array of all <em>arrayOfHexStringsAndArrayish</em> concatenated.</dd>
<dt><sup>utils</sup> . padZeros ( typedUint8Array, length )</dt>
<dd>Return a Uint8Array of <em>typedUint8Array</em> with zeros prepended to <em>length</em> bytes.</dd>
<dt><sup>utils</sup> . stripZeros ( hexStringOrArrayish )</dt>
<dd>Returns a Uint8Array with all leading zero <strong>bytes</strong> striped.</dd>
</dl>
<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 )</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>
</dl>
</div>
<hr class="docutils" />
<div class="section" id="contract-addresses">
<h2>Contract Addresses<a class="headerlink" href="#contract-addresses" title="Permalink to this headline"></a></h2>
<p>Every contract deployed on the Ethereum network requires an address (you can think
of this as the memory address which the running application lives at). The address
is generated from a cryptographic hash of the address of the creator and the nonce
of the transaction.</p>
<dl class="docutils">
<dt><sup>utils</sup> . getContractAddress ( transaction )</dt>
<dd>Computes the contract address a contract would have if this transaction
created a contract. (transaction requires only <code class="docutils literal"><span class="pre">from</span></code> and <code class="docutils literal"><span class="pre">nonce</span></code> be
defined)</dd>
</dl>
<div class="section" id="id6">
<h3><em>Examples</em><a class="headerlink" href="#id6" title="Permalink to this headline"></a></h3>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">var</span> <span class="n">utils</span> <span class="o">=</span> <span class="n">require</span><span class="p">(</span><span class="s1">&#39;ethers&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">utils</span><span class="p">;</span>
<span class="o">//</span> <span class="n">Ropsten</span><span class="p">:</span> <span class="mh">0x5bdfd14fcc917abc2f02a30721d152a6f147f09e8cbaad4e0d5405d646c5c3e1</span>
<span class="n">var</span> <span class="n">transaction</span> <span class="o">=</span> <span class="p">{</span>
<span class="n">from</span><span class="p">:</span> <span class="s1">&#39;0xc6af6e1a78a6752c7f8cd63877eb789a2adb776c&#39;</span><span class="p">,</span>
<span class="n">nonce</span><span class="p">:</span> <span class="mi">0</span>
<span class="p">};</span>
<span class="n">console</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">utils</span><span class="o">.</span><span class="n">getContractAddress</span><span class="p">(</span><span class="n">transaction</span><span class="p">));</span>
<span class="o">//</span> <span class="s2">&quot;0x0CcCC7507aEDf9FEaF8C8D731421746e16b4d39D&quot;</span>
</pre></div>
</div>
<hr class="docutils" />
</div>
</div>
</div>
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