?(子表达式)需要执行的表达式
例:(abc)2333(?(1)\w)
Only when the subexpression matches successfully, the following expression will be matched. Does js support this writing method? If you try it, an error will be reported directly.
我想大声告诉你2017-05-19 10:42:26
Unfortunately, Javascript is not supported currently. C#, php, python, etc. all support this advanced syntax.