Creating regexp with special characters

Question

I'm creating a query for mongodb:

app.get('content/:title',
function(req, res) {
  var regexp = new RegExp(req.params.title, 'i');

  db.find({
    "title": regexp,
  }).toArray(function(err, array) {
    res.send(array);
  });
});

But sometimes the title has a parenthese in it. This gives me the error:

SyntaxError: Invalid regular expression: /cat(22/: Unterminated group
    at new RegExp (unknown source)

The title that is being searched for is cat(22).

What's the easiest way to make the regex accept parenthesis? Thanks.

You need to escape the parentheses in your pattern: i.e., `(` should be `\(`, otherwise the regex engine thinks it's an opening group character. There are a number of special characters you will need to escape: a quick Google found [this](http://simonwillison.net/2006/Jan/20/escape/#p-6), for example. — Xophmeister, Jan 16 '12 at 16:07
...Also see: http://stackoverflow.com/questions/3446170/escape-string-for-use-in-javascript-regex — Xophmeister, Jan 16 '12 at 16:08

score 14 · Accepted Answer · edited May 23 '17 at 12:00

14

You can escape all possible regex special characters with code borrowed from this answer.

new RegExp(req.params.title.replace(/([.?*+^$[\]\\(){}|-])/g, "\\$1"), "i");

edited May 23 '17 at 12:00

Community

1
1

answered Jan 16 '12 at 16:07

1

I edited the regex to include the `|` character which means union in a regular expression body. Anyone using the version without `|` might have subtle bugs. – Mike Samuel Jan 16 '12 at 16:27
@WayneConrad: If you mean `escape(...)`, then no, that's different. – Jan 16 '12 at 16:55

TuK · Answer 2 · 2012-01-16T16:19:10.270

1

Escape it with a backslash. And test it on a site like http://rejex.heroku.com/

/cat\(22/

edited Jan 16 '12 at 16:19

answered Jan 16 '12 at 16:07

TuK

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Creating regexp with special characters

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