Creating javascript regex tp replace characters using whitelist

Question

I'm trying to create a regex which will replace all the characters which are not in the specified white list (letters,digits,whitespaces, brackets, question mark and explanation mark)
This is the code :

var regEx = /^[^(\s|\w|\d|()|?|!|<br>)]*?$/;
    qstr += tempStr.replace(regEx, '');

What is wrong with it ?

Thank you

What do you intend to do with <br>s?

Tim Pietzcker
– Tim Pietzcker

2013-07-31 15:05:45 +00:00
Commented Jul 31, 2013 at 15:05 — Tim Pietzcker
– Tim Pietzcker, Commented Jul 31, 2013 at 15:05

Tim Pietzcker · Accepted Answer · 2013-07-31 15:06:38Z

7

The anchors are wrong - they only allow the regex to match the entire string
The lazy quantifier is wrong - you wouldn't want the regex to match 0 characters (if you have removed the anchors)
The parentheses and pipe characters are wrong - you don't need them in a character class.
The <br> is wrong - you can't match specific substrings in a character class.
The \d is superfluous since it's already contained in \w (thanks Alex K.!)
You're missing the global modifier to make sure you can do more than one replace.
You should be using + instead of * in order not to replace lots of empty strings with themselves.

Try

var regEx = /[^\s\w()?!]+/g;

and handle the <br>s independently (before that regex is applied, or the brackets will be removed).

edited Jul 31, 2013 at 15:06

answered Jul 31, 2013 at 14:37

Tim Pietzcker

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1 Comment

Alex K. Over a year ago

I think \w encompasses \d also

Halcyon · Accepted Answer · 2013-07-31 14:36:54Z

0

You'll want to use the g (global) modifier:

var regEx = /^[^(\s|\w|\d|()|?|!|<br>)]*?$/g; // <-- `g` goes there
qstr += tempStr.replace(regEx, '');

This allows your expression to match multiple times.

answered Jul 31, 2013 at 14:36

Halcyon

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