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

Question

From the following markup.

    Somewhere
    Somewher         


        

                      

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Answer 1

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 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

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 4

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);