Jquery regexp dynamic expression

Question

I have this regexp :

var regexp = /(2\d)(\W)/gi

Now I want to set it dynamically, meaning the value 2 can be changed like this :

var regexp = /(changablevalue\d)(\W)/gi

I tried :

var regexp = "/(" + changablevalue + "\d)(\W)/gi"

and

var changablevalue = 2
var regexp = /(changablevalue\d)(\W)/gi

but can't get it to work. What am I doing wrong here?

Avinash Raj · Accepted Answer · 2014-11-06 06:53:18Z

1

Pass your regex to RegExp constructor.

var regex = new RegExp("("+changablevalue + "\\d)(\\W)", "gi")

Example:

> var changablevalue = 2
> var regex = new RegExp("("+changablevalue + "\\d)(\\W)", "gi")
undefined
> console.log(regex)
/(2\d)(\W)/gi
undefined
> regex.test('28.')
true
> regex.test('48.')
false

edited Nov 6, 2014 at 6:53

answered Nov 6, 2014 at 6:48

Avinash Raj

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3 Comments

NeedAnswers Over a year ago

It still not working, do I need to install some additional classes?

NeedAnswers Over a year ago

Ah I see, the slashes

Michal Leszczyk Over a year ago

Since in the constructor you're passing the regex as a string, I believe that backslashes should be escaped. And so should the changeablevalue (if it will contain any "regex expressions", like \w for example.)

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