How do I "unstringify" a value within an array with javascript?

Question

I'm building a dynamic search query for a Mongo database.

In short, and not directly related to the question... it looks like this:

var searchCriteria = {}; <-- start with empty object    

return db.users.find(searchCriteria,
    { sort: { username: 1 }
});

The values for searchCriteria come from a search form, basically like this:

var filter = $(form).find('select[name=filter]').val();
var query = $(form).find('[name=query]').val();

searchCriteria[filter] = query <-- Using a dynamic key

Example output from the form:

console.log(searchCriteria);
>> { username: "jdoe" }

So here's my hangup. I need to "unstringify" the query within the searchCriteria, and turn it into this:

>> { username: /jdoe/ }

I've tried replace, among other things, but it keeps ending up as a string value. I need the /query/ in that format for the Mongo find query.

Any suggestions? Thank you :)

Huh? Are you trying to turn a string into a Regex? If so, just new RegExp(string); — Zoey Mertes
– Zoey Mertes, Commented Oct 7, 2014 at 18:08
is there a reason why you need this ? may there is a option for other possibilitys to solve this if we know what you want to do with it :) — Dwza
– Dwza, Commented Oct 7, 2014 at 18:11
@ZekeSonxx I can't believe I missed this... How embarrassing. Please post as answer and I'll accept. — user1447679
– user1447679, Commented Oct 7, 2014 at 18:11

Zoey Mertes · Accepted Answer · 2014-10-07 18:18:40Z

1

You can easily turn a string into a RegExp object by using new Regex(string).

Note that this is bound to have some security issues somewhere if you're passing in user input, but new RegExp shouldn't allow any arbitrary JS to run, but it could still crash your code by being an invalid Regex.

Source (MDN)

edited Oct 7, 2014 at 18:18

answered Oct 7, 2014 at 18:12

Zoey Mertes

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3 Comments

dandavis Over a year ago

someone should probably mention something about escaping special chars and sanitizing user input.

user1447679 Over a year ago

@dandavis Good call. In my case, it's a protected admin page on a site.

user1447679 Over a year ago

@dandavis Hah. Me either :)

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