Question

I’m using following code to alert id of current element.

<input type="text" id="desc" name="txtTitle" onclick="fun()">

jquery:

function fun () {
    var currentId = $(this).attr('id');
    alert(currentId);
}

Why does it alert “undefined”?
I have tried with:

var currentId =$('element').attr('id'); 
// and 
alert($(this).id); 
// and 
alert(this.id);

but it alerts undefined

Answer 1

Try changing it to:

<input type="text" id="desc" name="txtTitle" onclick="fun.call(this)">

Better, bind your event handler with jQuery, since you’re using it anyway:

$(function() { $('#desc').click(fun); });

The reason your code doesn’t work is that you’re calling fun() from inside the event handler function constructed by the browser for your “onclick” attribute. By just calling the function like that, you provide no “receiver” object — nothing for this to be, that is. If you call it with .call() however you can explicitly do that.