Question

I have some inputs as below:

<input type="hidden" id="selected_id-1" name="id[]" />
<input type="hidden" id="selected_id-2" name="id[]" />
<input type="hidden" id="selected_id-3" name="id[]" />
<input type="hidden" id="selected_id-5" name="id[]" />

The list can contain more than just 4 elements.

So, I would like to extract the highest number (in our case = 5) from the ids of elements named “id”.

Pure JavaScript needed.

EDIT: Thank you everybody who answered my question.

Answer 1

Assuming your elements might not be ordered by id, you’ll have to check them all to find the highest one.

var inputs = document.getElementsByTagName('input');
var highest = 0;
for(var i=0; i<inputs.length; i++) {
    if(inputs[i].name == 'id[]') {
        var current = inputs[i].id.split('-')[1];
        highest = (current > highest) ? current : highest;
    }
}
// Now highest contains the highest numeric id
console.log(highest);