如何在正则表达式中使用变量

Question

I have following RegExp and it is working fine

 var reg = new RegExp(/(.{1,4})/g);

But now i want to replace 4 with variable called limit then it is not working

 var reg = new RegExp("/(.{1,"+ limit +"})/g");

How could i use variable instead of fixed value in above RegExp?

Answer 1

Drop the / . RegExp expects a string or a regex. Then it takes a second parameter where you can specify the flags.

var reg = new RegExp("(.{1,"+ limit +"})", "g");

More here https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Regular_Expressions

Answer 2

这样（您不需要/ ）：

 var reg = new RegExp(".{1,"+ limit +"}", "g");

Answer 3

Use it like this,

var reg = new RegExp("(.{1,"+ limit +"}", "g");

The second parameter is used for options. And the pattern does not take any delimiter.