Undefined var in IE8 javascript/jQuery

Question

I'm having a bit of an issue with IE8 and jQuery 1.9.1.

The target browser is IE8. I get an undefined variable when I try to alert the rolevalue var.

Here's the code:

function get_role(){
    var test = document.getElementsByName("admin_role");
    for(var elem in test){
        if(test[elem].checked){
            var rolevalue = test[elem].value;
            $.post('<?php echo base_url(); ?>ajaxsc/getrole/',{role:rolevalue},function(result){
                $('#roletest').html(result);
                });
        }
    }
    **alert('role = ' + rolevalue);**
    return rolevalue;
}

Watch out about the scope of the current variable, if everything else fails, declare it empty at the top of your get_role function — Arthur Kovacs
– Arthur Kovacs, Commented Aug 26, 2013 at 19:44
Try using a regular for loop rather than for..in for array-like collections. You may be getting more properties for elem than you expect. stackoverflow.com/questions/500504/… — Jonathan Lonowski
– Jonathan Lonowski, Commented Aug 26, 2013 at 19:48

Spudley · Accepted Answer · 2013-08-26 19:49:43Z

4

The problem is that the for..in loop is iterating over some unwanted items.

If you using a for..in loop, you need to be aware of this; you may get the loop iterating over object properties that are part of the object prototype rather than actual elements that you want to iterator over.

What is happening is that it's hitting an property in the loop that is not a DOM element, and of course, that means it doesn't have a .value, so when you try to set the variable from .value, you get undefined.

To avoid this, you need to use the .hasOwnProperty() method to determine whether the loop is iterating a prototype method, and avoid them. You need to do something like this:

for (var i in obj) {
    if (obj.hasOwnProperty(i)) {
        .....
    }
}

Hope that helps.

answered Aug 26, 2013 at 19:49

Spudley

169k39 gold badges240 silver badges309 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user400654 Over a year ago

Or, you could instead iterate over the collection using an index loop rather than a for in loop.

Collectives™ on Stack Overflow

Undefined var in IE8 javascript/jQuery

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related