Bump to v4.0.0.

escapeRegExp.js

@@ -0,0 +1,29 @@
+define(['./toString'], function(toString) {
+
+  /** Used to match `RegExp` [syntax characters](http://ecma-international.org/ecma-262/6.0/#sec-patterns). */
+  var reRegExpChar = /[\\^$.*+?()[\]{}|]/g,
+      reHasRegExpChar = RegExp(reRegExpChar.source);
+
+  /**
+   * Escapes the `RegExp` special characters "^", "$", "\", ".", "*", "+",
+   * "?", "(", ")", "[", "]", "{", "}", and "|" in `string`.
+   *
+   * @static
+   * @memberOf _
+   * @category String
+   * @param {string} [string=''] The string to escape.
+   * @returns {string} Returns the escaped string.
+   * @example
+   *
+   * _.escapeRegExp('[lodash](https://lodash.com/)');
+   * // => '\[lodash\]\(https://lodash\.com/\)'
+   */
+  function escapeRegExp(string) {
+    string = toString(string);
+    return (string && reHasRegExpChar.test(string))
+      ? string.replace(reRegExpChar, '\\$&')
+      : string;
+  }
+
+  return escapeRegExp;
+});