ansaurus

Question

Answer 1

+2 A:

Firebug is your friend....

i is not defined

function onchange(event) { parent.nowplaying(this.SelectedIndex, i); }(change )

onchange is getting called, but i is not defined when calling nowplaing.

This is the result of this line:

p+="<html><head></head><body><form><select onchange='parent.nowplaying(this.SelectedIndex,i);' size='";

which is using "i" in the string, when it should append it as a variable:

p+="<html><head></head><body><form><select onchange='parent.nowplaying(this.SelectedIndex," + i + ");' size='";

To clarify, i is defined when anything(i) is called, but you aren't writing i into the code, just the letter i. When nowplaying(this.SelectedIndex,i) is called, i is no longer defined, because you aren't inside of the anything() function anymore. You need to expand i when you append the html to p, so that the value is there and not the variable i.

Jeff B 2009-11-25 21:10:03

But "i" is defined...it's the value that I'm passing into the function "anything" ?

Deacon 2009-11-25 21:13:58

The problem is that you are using "i" as a string and not a variable. You are doing p+="blah blah i blah", instead of p+="blah blah "+i+" blah". See my edits.

Jeff B 2009-11-25 21:16:25

Thanks. I've now tried it with that edit, and I get the error console saying "mymusic[albumindex].tracks[trackindex].tracktitle is undefined"...but I can't see how it's undefined as the mymusic and tracks arrays are defined, and albumindex and trackindex should both take the value of numbers being passed into the function

Deacon 2009-11-25 21:22:49

You need to add parent to that. You are calling it from the context of the frame:parent.mymusic[albumindex].tracks[trackindex].tracktitle

Jeff B 2009-11-25 21:25:08

Thanks again for your reply. I've just done that for both of the instances where i mentioned "mymusic...." within function nowplaying, and it still doesn't write to the iframe...i put an alert(q) in after I've finished building q, and that doesn't happen either. So I really don't know what's up now!

Deacon 2009-11-25 21:29:54

Can you post a new link?

Jeff B 2009-11-25 21:31:33

http://www.wikiupload.com/download_page.php?id=196269I guess the crux of my frustration is, why isn't it working the second time, if it works the first time, and I'm doing it exactly the same?!Thanks so much for your help

Deacon 2009-11-25 21:38:12

this.SelectedIndex should be this.selectedIndex

Jeff B 2009-11-25 21:53:15

Oh dear! I can't believe it was something as trivial as that, most likely a typing error on my part. Thank you very much for your help, I really appreciate you taking the time to go through it yourself :-) Cheers

Deacon 2009-11-25 21:56:00

No problem. Just be sure to accept my answer. ;)

Jeff B 2009-11-25 21:57:42

Answer 2

A:

function anything(i){
    p+="...<select onchange='parent.nowplaying(this.SelectedIndex,i);'...";

Your onchange event handler is set from a string. When run, it will not have access to i, which is a local variable from the anything function that has long since gone away.

The simple fix would be:

    p+="...<select onchange='parent.nowplaying(this.SelectedIndex,'+i+');'...";

which turns the current value of i at string-making time into an integer literal inside the string.

However, it's not generally a good idea to be creating code from strings. It's normally better to write the event handler as a normal function object:

// You will need the below workaround to get the iframe document in IE too
//
var iframe= document.getElementById('songs');
var idoc= 'contentDocument' in iframe? iframe.contentDocument : iframe.contentWindow.document;

idoc.open();
idoc.write(s);
idoc.close();

idoc.getElementsByTagName('select')[0].onchange= function() {
    // This is a closure. The 'i' variable from the parent 'anything' function is
    // still visible in here
    //
    parent.nowplaying(this.selectedIndex, i);
};

However you would generally want to avoid setting handlers from one frame on a different one. I'm not really sure what the iframes are gaining you here other than headaches. Why not just simply use positioned divs with overflow? You can still rewrite their content through innerHTML if you need to... though I would prefer to populate them using DOM methods, to avoid all the HTML-injection problems your current script has.

bobince 2009-11-25 21:22:31

ansaurus

tags:

views:

answers:

onchange attribute won't call function

related questions