--- /dev/null
+define(['../lang/toNumber'], function (toNumber) {
+
+ /**
+ * Get sign of the value.
+ */
+ function sign(val) {
+ var num = toNumber(val);
+ if (num === 0) return num; // +0 and +0 === 0
+ if (isNaN(num)) return num; // NaN
+ return num < 0? -1 : 1;
+ }
+
+ return sign;
+
+});