Question

I have the following code:

var requestData = {};

var byPattern = /by=(\w+)/;
var value = byPattern.exec(stringToSearch);
if (value && value.length === 2)
    requestData.by = value[1];

The first problem with this regex, was that if stringToSearch is for example “standby=foo”, it matched and returned “foo”. I want it to fail there. I want the regex to match only if there is nothing before “by”, or spaces.

So I replaced by /^\s*by=(\w+)/

That’s better, but I want the regex to match if stringToSearch is for example “city=paris by=foo”. It should match and return “foo”. Not the case here :/

Can someone help me fix the regex? Thanks a lot!

Answer 1

If you want spaces or nothing before the capturing group, that would be ( +|^):

/( |^)by=(\w+)/

Technically, I’m matching space or nothing, but the effect is the same.