Bump to v4.0.0.

eq.js

@@ -0,0 +1,38 @@
+define([], function() {
+
+  /**
+   * Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
+   * comparison between two values to determine if they are equivalent.
+   *
+   * @static
+   * @memberOf _
+   * @category Lang
+   * @param {*} value The value to compare.
+   * @param {*} other The other value to compare.
+   * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
+   * @example
+   *
+   * var object = { 'user': 'fred' };
+   * var other = { 'user': 'fred' };
+   *
+   * _.eq(object, object);
+   * // => true
+   *
+   * _.eq(object, other);
+   * // => false
+   *
+   * _.eq('a', 'a');
+   * // => true
+   *
+   * _.eq('a', Object('a'));
+   * // => false
+   *
+   * _.eq(NaN, NaN);
+   * // => true
+   */
+  function eq(value, other) {
+    return value === other || (value !== value && other !== other);
+  }
+
+  return eq;
+});