Bump to v4.0.0.

escapeRegExp.js

@@ -0,0 +1,28 @@
+import toString from './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;
+}
+
+export default escapeRegExp;