The JavaScript exception "invalid regular expression flag" occurs when the flags in a regular expression contain any flag that is not one of: d, g, i, m, s, u, v, or y. It may also be raised if the expression contains more than one instance of a valid flag, or when the u and v flags are used together....the regular expression literal: js const re = /pattern/flags; They...RegExp object (second parameter): js const re = new RegExp("pattern"...