Merge pull request #101 from stcherenkov/master

Add isBigNumber method

bignumber.js

@@ -328,6 +328,19 @@
         BigNumber.ROUND_HALF_FLOOR = 8;
         BigNumber.EUCLID = 9;
 
+        /*
+         * Check if passed instance is BigNumber
+         *
+         * @param {*} instance - what to check
+         * @returns {boolean}
+         */
+        BigNumber.isBigNumber = function (instance) {
+            if (!instance || !instance._isBigNumberInstance) {
+                return false;
+            }
+
+            return true;
+        }
 
         /*
          * Configure infrequently-changing library-wide settings.
@@ -2549,6 +2562,8 @@
             return n.s < 0 ? '-' + str : str;
         };
 
+        P._isBigNumberInstance = true;
+
 
         // Aliases for BigDecimal methods.
         //P.add = P.plus;         // P.add included above

doc/API.html

@@ -86,6 +86,7 @@ li span{float:right;margin-right:10px;color:#c0c0c0}
       <li><a href="#max"    >max</a></li>
       <li><a href="#min"    >min</a></li>
       <li><a href="#random" >random</a></li>
+      <li><a href="#is-big-number" >isBigNumber</a></li>
     </ul>
 
     <a href="#constructor-properties">Properties</a>
@@ -744,6 +745,21 @@ BigNumber.random(20)            // '0.78193327636914089009'</pre>
 
 
 
+    <h5 id="is-big-number">
+      isBigNumber<code class='inset'>.isBigNumber(instance) <i>&rArr; boolean</i></code>
+    </h5>
+    <p><code>instance</code>: <i>any</i></p>
+    <p>
+      Checks if passed instance is BigNumber.
+    </p>
+    <pre>BigNumber.isBigNumber(42)                  // false
+BigNumber.isBigNumber(new BigNumber('42')) // true
+
+var BN = BigNumber.another();
+BigNumber.isBigNumber(new BN('42'))        // true</pre>
+
+
+
     <h4 id="constructor-properties">Properties</h4>
     <p>
       The library's enumerated rounding modes are stored as properties of the constructor.<br />

test/every-test.js

@@ -37,7 +37,8 @@ console.log( '\n STARTING TESTS...\n' );
   'toNumber',
   'toPrecision',
   'toString',
-  'trunc'
+  'trunc',
+  'isBigNumber'
 ]
 .forEach( function (method) {
     arr = require('./' + method);

test/isBigNumber.js

@@ -0,0 +1,80 @@
+var count = (function isBigNumber(BigNumber) {
+    var start = +new Date(),
+        log,
+        error,
+        u,
+        passed = 0,
+        total = 0;
+
+    if (typeof window === 'undefined') {
+        log = console.log;
+        error = console.error;
+    } else {
+        log = function (str) { document.body.innerHTML += str.replace('\n', '<br>') };
+        error = function (str) { document.body.innerHTML += '<div style="color: red">' +
+          str.replace('\n', '<br>') + '</div>' };
+    }
+
+    if (!BigNumber && typeof require === 'function') BigNumber = require('../bignumber');
+
+    function assert(expected, actual) {
+        total++;
+        if (expected !== actual) {
+           error('\n Test number: ' + total + ' failed');
+           error(' Expected: ' + expected);
+           error(' Actual:   ' + actual);
+           //process.exit();
+        } else {
+            passed++;
+            //log('\n Expected and actual: ' + actual);
+        }
+    }
+
+    function assertException(func, message) {
+        var actual;
+        total++;
+        try {
+            func();
+        } catch (e) {
+            actual = e;
+        }
+        if (actual && actual.name == 'BigNumber Error') {
+            passed++;
+            //log('\n Expected and actual: ' + actual);
+        } else {
+            error('\n Test number: ' + total + ' failed');
+            error('\n Expected: ' + message + ' to raise a BigNumber Error.');
+            error(' Actual:   ' + (actual || 'no exception'));
+            //process.exit();
+        }
+    }
+
+    function T(expected, value){
+        assert(expected, BigNumber.isBigNumber(value));
+    }
+
+    log('\n Testing isBigNumber...');
+
+    T(false, u);
+    T(false, void 0);
+    T(false, null);
+    T(false, '0');
+    T(false, 0);
+    T(false, 1);
+    T(false, NaN);
+
+    T(true, new BigNumber(0));
+    T(true, new BigNumber('0'));
+    T(true, new BigNumber(1));
+    T(true, new BigNumber('1'));
+
+    var AnotherBigNumber = BigNumber.another();
+    T(true, new AnotherBigNumber(0));
+    T(true, new AnotherBigNumber('0'));
+    T(true, new AnotherBigNumber(1));
+    T(true, new AnotherBigNumber('1'));
+
+    log('\n ' + passed + ' of ' + total + ' tests passed in ' + (+new Date() - start) + ' ms \n');
+    return [passed, total];
+})(this.BigNumber);
+if (typeof module !== 'undefined' && module.exports) module.exports = count;