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....contain any flag that is not one of: d , g , i , m , s , u , v...expression contains more than one instance of a valid flag, or...