Question

How can i read the last element id using javascript?

for example :

          <div id='print'>

                <p id=1>some data</p>
                <p id=2>some data</p>
                <p id=3>some data</p>
                <p id=4>some data</p>
                <p id=5>some data</p>

          </div>

I need to detect the id of last

I need max number of the id actually.it’s generated sequentially.

Answer 1

First off, id values cannot be numbers. They must start with a non-number.

You can get the last child with this plain javascript (no jQuery required):

var lastChild = document.getElementById("print").lastChild;
var lastChildID = lastChild.id;

or in one line, it would be this:

var lastChildID = document.getElementById("print").lastChild.id

FYI, in case you need access to any other children you can always get all the children and then fetch the one you want:

var children = document.getElementById("print").children;
if (children.length > 1) {
    var first = children[0];
    var last = children[children.length - 1];
    var second = children[1];
}

Now that you’ve explained what you’re really trying to do, I’d suggest this:

 <div id='print'>
     <p data-num="1">some data</p>
     <p data-num="2">some data</p>
     <p data-num="3">some data</p>
     <p data-num="4">some data</p>
     <p data-num="5">some data</p>
 </div>

And, then this javascript:

var lastValue = document.getElementById("print").lastChild.getAttribute("data-num");

Using the data-xxx format is forward compatible with the HTML5 specification and usable in older browsers with getAttribute().