RegExp.prototype.flags

The flags property returns a string consisting of the flags of the current regular expression object.

Flags in the flags property are sorted alphabetically (from left to right, e.g. "gimsuy").

/foo/ig.flags;   // "gi"
/bar/myu.flags;  // "muy"

if (RegExp.prototype.flags === undefined) {
  Object.defineProperty(RegExp.prototype, 'flags', {
    configurable: true,
    get: function() {
      return this.toString().match(/[gimsuy]*$/)[0];
    }
  });
}

• RegExp.prototype.source