for loop in Internet Exporer has no value

Question

I have an old application that didnt use jquery.

so is an HTML select object.

This code gives an error, that value is not set in the second line of:

for (var i in so.options){
        if(so.options[i].value=='X') {
            // do something
        }
}

It works in Firefox though. How can I catch this without jquery?

Read this [SO question](http://stackoverflow.com/questions/500504/why-is-using-for-in-with-array-iteration-such-a-bad-idea) and this [SO question](http://stackoverflow.com/questions/3010840/loop-through-array-in-javascript?rq=1) — Max Brodin, Feb 25 '15 at 12:09

score 0 · Answer 1 · edited May 23 '17 at 12:20

0

You can also be clever. for(var i = 0, l = myArray.length; i < l; ++i) ... is the fastest and best you can get with forward iteration.

So my solution for IE and FF:

for(var i = 0, l = so.options.length; i < l; ++i){
    if(so.options[i].value=='X') {
        // do something
    }
}

edited May 23 '17 at 12:20

Community

answered Feb 25 '15 at 12:13

rubo77

score 0 · Answer 2 · answered Feb 25 '15 at 12:16

0

This is probably because the first property of so.options is the .length property, which is numeric and not an object.

To iterate an HTMLOptionsCollection, you need to do it like this:

for (var i = 0; i < so.options.length; ++i) {
    if (so.options.item(i).value == 'X') {
    }
}

Most browsers will probably provide a convenience accessor, though, so so.options[i].value should work as well.

answered Feb 25 '15 at 12:16

Ja͢ck

Where's the i++ in the loop? – geekpradd Feb 25 '15 at 12:19
I was going to edit it but you've disabled it. Sure no problem. – geekpradd Feb 25 '15 at 12:25
@geekpradd I didn't disable anything, it's probably due to your reputation score being too low to suggest edits? – Ja͢ck Feb 25 '15 at 12:30

2 Answers2