Document the radix argument of _.parseInt and ensure it ignores leading whitespace. [closes #254]

Former-commit-id: b1d0f7688402b3f41cfb030c63dcd097ba3f4e68

lodash.js

@@ -55,8 +55,20 @@
   /** Used to match "interpolate" template delimiters */
   var reInterpolate = /<%=([\s\S]+?)%>/g;
 
-  /** Used to match leading zeros to be removed */
-  var reLeadingZeros = /^0+(?=.$)/;
+  /** Used to detect and test whitespace */
+  var whitespace = (
+    // whitespace
+    ' \t\x0B\x0C\xA0\ufeff' +
+
+    // line terminators
+    '\n\r\u2028\u2029' +
+
+    // unicode category "Zs" space separators
+    '\u1680\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000'
+  );
+
+  /** Used to match leading whitespace and zeros to be removed */
+  var reLeadingSpacesAndZeros = RegExp('^[' + whitespace + ']*0+(?=.$)');
 
   /** Used to ensure capturing order of template delimiters */
   var reNoMatch = /($^)/;
@@ -1277,7 +1289,6 @@
      */
     var defaults = createIterator(defaultsIteratorOptions);
 
-
     /**
      * This method is similar to `_.find`, except that it returns the key of the
      * element that passes the callback check, instead of the element itself.
@@ -4878,6 +4889,8 @@
 
     /**
      * Converts the given `value` into an integer of the specified `radix`.
+     * If `radix` is `undefined` or `0`, a `radix` of `10` is used unless the
+     * `value` is a hexadecimal, in which case a `radix` of `16` is used.
      *
      * Note: This method avoids differences in native ES3 and ES5 `parseInt`
      * implementations. See http://es5.github.com/#E.
@@ -4885,16 +4898,17 @@
      * @static
      * @memberOf _
      * @category Utilities
-     * @param {Mixed} value The value to parse.
+     * @param {String} value The value to parse.
+     * @param {Number} [radix] The radix used to interpret the value to parse.
      * @returns {Number} Returns the new integer value.
      * @example
      *
      * _.parseInt('08');
      * // => 8
      */
-    var parseInt = nativeParseInt('08') == 8 ? nativeParseInt : function(value, radix) {
+    var parseInt = nativeParseInt(whitespace + '08') == 8 ? nativeParseInt : function(value, radix) {
       // Firefox and Opera still follow the ES3 specified implementation of `parseInt`
-      return nativeParseInt(isString(value) ? value.replace(reLeadingZeros, '') : value, radix || 0);
+      return nativeParseInt(isString(value) ? value.replace(reLeadingSpacesAndZeros, '') : value, radix || 0);
     };
 
     /**