validation of javascript regular expression

Question

I have the following string of javascript:

#d1{width:100px;} it looks like css code

now I wrote a regular expression that finds of an element starting with # or . in the string.

the regular expression is like this:

/(?:(#|\.)([A-Za-z0-1\-]+))/g

and the above regular expression matches successfully such strings like the above one.

but now when I tested this regular expression on the above string in Google console with then it returns false

the which I wrote was:

var str = "#d1{width:100px} " // returns undefined
var regex = / (?:(#|\.)([A-Za-z0-1\-]+)) /g //undefrined
regex.test(str) // returns false

Why it is not working?

have you tried it without the spaces? regex = /(?:(#|\.)([A-Za-z0-1\-]+))/g? — lordvlad
– lordvlad, Commented Dec 5, 2014 at 9:23

lordvlad · Accepted Answer · 2014-12-05 09:25:26Z

4

You have spaces in your regular expression which you propably don't want there:

var str = "#d1{width:100px} " // returns undefined
var regex = /(?:(#|\.)([A-Za-z0-1\-]+))/g //undefrined
//           ^-------------------------^----- see, no spaces here
regex.test(str) // returns true

answered Dec 5, 2014 at 9:25

lordvlad

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1 Comment

Avinash Raj Over a year ago

you don't need to go for capturing or non-capturing groups. Just [#.][A-Za-z0-1-]+ would be fine.

Emre Acar · Accepted Answer · 2014-12-05 09:27:19Z

1

Try this. These spaces between / and parantheses are jerks.

function regtest()
{
var str = "#d1{width:100px}" // returns undefined
var regex = /(?:(#|\.)([A-Za-z0-1\-]+))/g //undefrined
alert(regex.test(str));
}

<button onclick="regtest()">Test</button>

answered Dec 5, 2014 at 9:27

Emre Acar

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