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I'm working on some regex for a input text field and have had some trouble escaping special characters such as "+" or "?".

I've used these two questions for doing so and they work for a string such as c+ but if I enter c++ I get following error in the console Invalid regular expression: /c++/: Nothing to repeat

Here's the code:

$('input').keyup(function(){
   var val = $(this).val().trim().toLowerCase();
    // from: http://stackoverflow.com/questions/3561493/is-there-a-regexp-escape-function-in-javascript
    //val.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');

    //from: http://stackoverflow.com/questions/3446170/escape-string-for-use-in-javascript-regex
    val = val.replace(/[\-\[\]{}()*+?.,\\\^$|#\s]/g, "\\$&");

    var re = new RegExp(val, 'ig');
    console.log(re);
});

Here is a jsFiddle example of the issue

Thanks

share|improve this question

2 Answers 2

up vote 1 down vote accepted

There's a bug in your code. As a string is immutable in JavaScript, replace doesn't change it but returns a new one. You do the replacement but you doesn't take the returned value

Change

val.replace(/[\-\[\]{}()*+?.,\\\^$|#\s]/g, "\\$&");

to 

val = val.replace(/[\-\[\]{}()*+?.,\\\^$|#\s]/g, "\\$&");

Demonstration

share|improve this answer
    
Oh yes of cause, I feel so silly. Thank you so much :-) – Mestika Jun 23 at 11:12
up vote 1 down vote

Your regex was fine, you just threw away the result of the replace call. Replace with val = val.replace(...);

Working fiddle

share|improve this answer
    
Thank you so much - it was so easy :-) – Mestika Jun 23 at 11:12

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