Question

I have a tree with checkboxes and their id has key for item and value as their value.

<input type="checkbox" name="list_code[4]" id="list_code[4]" value="AG12345678" checked="checked">

When users select a tree element I can access those by

$('input[name^="list_code"]').each(function() {
    if ($(this).attr('checked')) 
        list_code = $(this).val();
});

I am able to get value AG12345678 but I need to get key value too which is 4 from list_code[4] in this case. How can I access that value?

Answer 1

var n = this.id.slice(this.id.indexOf('[') + 1, this.id.indexOf(']'));

or…

var n = this.id.replace(/\D/g, '');

or…

var n = (this.id.match(/\d+/) || [])[0];

or if there could be other unwanted numbers…

var n = (this.id.match(/\[(\d+)\]/) || [])[1];

---

Or if you control the source, a good solution would be to use a data- attribute for future HTML5 support…

<input type="checkbox" data-number="4" name="list_code[4]" id="list_code[4]" value="AG12345678" checked="checked">

…then in HTML5 browsers, you could do…

this.data.number;

…or for legacy support, you could do…

this.getAttribute('data-number');