Why doesn't my getAttribute work ?

**brucewayne** · 09-28-2012, 10:06 AM

<html>
<head>
<script type="text/javascript>
var a = document.getElementsByTagName("img").getAttribute("src");
alert(a);
</script>
<body>
<img src="www.google.com" alt="picture"/>
</body>
</html>

I want the browser to alert the src of the picture (www.google.com) but it never works !
Help much appreciated
Thanks in advance,
B.W

**xelawho** · 09-28-2012, 01:40 PM

getElementsByTagName returns a collection (even if that collection is only one item, and the contents should be accessed by array notation.

getAttribute is only really necessary for non-standard attributes. The standard ones (like src) can be accessed directly:

Code:

var a = document.getElementsByTagName("img")[0].src;

**coothead** · 09-28-2012, 02:23 PM

Hi there brucewayne,

and a warm welcome to these forums.

Further to what xelawho has said, there are some other reasons for your script failure.

You are missing a closing double quote here...

...which means that the script will never run.

Although you can set this...

var a=document.getElementsByTagName('img');

...before the page loads, you cannot access the actual elements until after.

This following will resolve these issues...

Code:

<script type="text/javascript">

  var a=document.getElementsByTagName('img');

function init(){

for(c=0;c<a.length;c++) {
   alert(a[c].getAttribute('src'));
  }
 }
   window.addEventListener?
   window.addEventListener('load',init,false):
   window.attachEvent('onload',init);

</script>

coothead

**xelawho** · 09-28-2012, 02:25 PM

woops. never even looked that far. nice one, coothead

**coothead** · 09-28-2012, 02:30 PM

Hi there xelawho,

thanks for the thumbs-up.

coothead

**brucewayne** · 09-28-2012, 06:36 PM

Now, I don't understand all that window.onload code. So, to make it simpler for me, I'd like to use butttons.

HTML:

<img src="www.google.com" alt="picture"/>
<input type="button" onclick="alertit()"/>

Javascript:

<script type="text/javascript">
function alertit() {
var a = document.getElementsByTagName("img")[0].getAttribute("src");
alert(a);
}

Why doesn't this work either ?