Include minus sign for valueOf() negative zero

bignumber.js

@@ -2353,10 +2353,7 @@
          * Return the value of this BigNumber converted to a number primitive.
          */
         P.toNumber = function () {
-            var x = this;
-
-            // Ensure zero has correct sign.
-            return +x || ( x.s ? x.s * 0 : NaN );
+            return +this;
         };
 
 
@@ -2485,10 +2482,23 @@
 
 
         /*
-         * Return as toString, but do not accept a base argument.
+         * Return as toString, but do not accept a base argument, and include the minus sign for
+         * negative zero.
          */
         P.valueOf = P.toJSON = function () {
-            return this.toString();
+            var str,
+                n = this,
+                e = n.e;
+
+            if ( e === null ) return n.toString();
+
+            str = coeffToString( n.c );
+
+            str = e <= TO_EXP_NEG || e >= TO_EXP_POS
+                ? toExponential( str, e )
+                : toFixedPoint( str, e );
+
+            return n.s < 0 ? '-' + str : str;
         };
 
 

doc/API.html

@@ -1752,10 +1752,16 @@ y.trunc()                       // '-12'</pre>
 
 
     <h5 id="valueOf">valueOf<code class='inset'>.valueOf() <i>&rArr; string</i></code></h5>
-    <p>As <code>toString</code>, but does not accept a base argument.</p>
+    <p>
+      As <code>toString</code>, but does not accept a base argument and includes the minus sign
+      for negative zero.
+    </p>
     <pre>
-x = new BigNumber('1.777e+457')
-x.valueOf()                     // '1.777e+457'</pre>
+x = new BigNumber('-0')
+x.toString()                    // '0'
+x.valueOf()                     // '-0'
+y = new BigNumber('1.777e+457')
+y.valueOf()                     // '1.777e+457'</pre>
 
 
 

test/others.js

@@ -189,7 +189,9 @@ var count = (function others(BigNumber) {
     assert(false, n.lessThan(0, 36));
     assert(true, n.lessThan(0.1));
     assert(true, n.lessThanOrEqualTo(0));
-    assert(n.toString(), n.valueOf());
+    assert(true, n.valueOf() === '-0');
+    assert(true, n.toJSON() === '-0');
+    assert(true, n.toString() === '0');
 
     n = new BigNumber('NaN');
     assert(false, n.isFinite());