Regular expression for matching id selector using javascript

Question

In my program , i want to validate id of html tags.. To my functions id is passed as a string preceeding with #.. I found that ,rules for naming and id in HTML are,

Must begin with a letter A-Z or a-z
Can be followed by: letters (A-Za-z), digits (0-9), hyphens ("-"), and underscores ("_") So i written the following regular expression.

/(^|\s)(#{1})([a-zA-Z])([^a-zA-Z0-9]{0})/g;

But it is giving me wrong results.What's wrong with my regular expression?

What results do you get? Could you provide some sample input and corresponding output? — ctt
– ctt, Commented Apr 30, 2012 at 22:01
Note that many of these restrictions have been removed in html 5. — James Montagne
– James Montagne, Commented Apr 30, 2012 at 22:02

inhan · Accepted Answer · 2012-04-30 22:56:20Z

2

/#[a-z][\w\d-]*\b/gi

\w signifies letters from a-z, A-Z and underscore (_)
\d signifies whole numbers from 0-9
\b signifies a word boundary
the i flag is to catch the first letter regardless of case

EDIT: Sorry for forgetting the boundary in the beginning of the group.

var str = '#sss #s23 dd#ww';
// #ww will be omitted because # is not the
// first char in the char group there.
var rx = /(^|\s)(#[a-z][\w\d-]*)\b/gi;
var arr = [];
str.replace(rx, function(){arr.push(arguments[2])});
// this is just to catch the id's.
// it won't modify str.
for (var i = 0; i < arr.length; i++) {
    console.log(arr[i]);
}

edited Apr 30, 2012 at 22:56

answered Apr 30, 2012 at 22:43

inhan

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Comments

dynamic · Accepted Answer · 2012-04-30 22:01:49Z

1

try:

/^#[a-z]{1}[a-z0-9_-]*$/i

answered Apr 30, 2012 at 22:01

dynamic

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4 Comments

Jinu Joseph Daniel Over a year ago

this gives me correct result..but [a-z0-9_-] same as [^a-z0-9_-]{0}?. then why am i getting wrong results?

dynamic Over a year ago

@JinuJD: no, oblivious not the same

dynamic Over a year ago

Your solution with {0} is completly different from mine. I must say i struggle to understand what is the possibile result with your regex

Jinu Joseph Daniel Over a year ago

it should contain zero occurances of non alphanumeric_- at the end which is same as alphanumeric_- characters at the end

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