JavaScript/jQuery - grabbing an integer from an element's id

Question

From the following markup.

<div id="my-div">
    <a href="#" id="link-1">Somewhere</a>
    <a href="#" id="link-2">Somewhere else</a>
</div>

What are some options, using jQuery selectors and JavaScript for grabbing the integer in the ids?

For example.

$("#my-div a").click(function(){
    $(this).id // ... somehow grab n from "link-n"        
    alert(n);
});

Answer 1

$(this).attr('id').replace('link-','')

Answer 2

As long as the preceding text always remains the same you can just use the substring method to get the number.

$(this).attr('id').substring(5)

Answer 3

Using a regex would be your best option, for instance:

// id contains '1' for id="link-1"
var id = parseInt(this.id.replace(/[^\d]/g, ''), 10);

Answer 4

If you know that all your ids are prefixed by "link-", you can simply get the substring of the id:

$("#my-div a").click(function(){
   alert(this.id.substr(5));
});

Answer 5

I usually do something like this:

$("#my-div a").click(function(){
    var match;
    if (match = $(this).attr('id').match(/link-(\d+)/)) {
      var number = parseInt(match[1],10);
      alert(number);
    }
});

Answer 6

var match = /link-(\d+)/.exec($(this).attr('id'));
var num = match[1];

Answer 7

var id = $(this).attr('id'),
    regex = /(\d+)/,
    matched = id.match( regex );

if ( matched ) {
    alert( matched[1] )
}

Answer 8

$(this).attr('id').split('-')[1];

Answer 9

You could try:

var n = $(this).attr('id').match(/link-(\d+)/)[1];

This fetches the id attribute, matches against the pattern link-(\d+) (which means link- followed by one or more digits), and then extracts the first subexpression match (the part in the parentheses \d+), which should be the number you are looking for.

If you need to work with n as an integer instead of a string, you should should use parseInt, making sure to specify base 10:

var n = parseInt($(this).attr('id').match(/link-(\d+)/)[1], 10);

If your id attributes are not guaranteed to begin with link- followed by one or more digits, and you would like to catch this case instead of throwing an error, you should check the return value of match:

var match = $(this).attr('id').match(/link-(\d+)/);
if (match) {
    var n = parseInt(match[1], 10);
    alert(n);
} else {
    // do something else if they don't match
}

Answer 10

This should be the simplest way:

var id = this.id.replace(/[^\d]/g,'')*1;

It returns any digits from the ID attribute as a number (*1 does the conversion, similar to parseInt). In your example:

$("#my-div a").click(function(){
    var n = this.id.replace(/[^\d]/g,'')*1;
    alert(n);  // alerts any number in the ID attribute
    alert(typeof n) // alerts 'number' (not 'string')
});