background image based on screen resolution

[rsines]

Can someone tell me what is wrong with this script. I want a different size background image to appear based on users screen resolution.

<script language="JavaScript1.2">
<!--
if (screen.width==640||screen.height==480 && document.all||document.getElementById)
document.body.style.background="url('640_bkg.gif') white bottom no-repeat fixed"

else if (screen.width==800||screen.height==600 && document.all||document.getElementById) 
document.body.style.background="url('800_bkg.gif') white bottom no-repeat fixed"

else if (screen.width==1024||screen.height==768 && document.all||document.getElementById) 
document.body.style.background="url('1024_bkg.gif') white bottom no-repeat fixed"

else if (document.all||document.getElementById)
document.body.style.background="url('1280_bkg.gif') white bottom no-repeat fixed" 
//-->
</script>

[forum_amnesiac]

If you just want to detect the screen resolution I think you just need to detect the height & width. eg

if (screen.width==640||screen.height==480)

You should also finish with an ELSE to catch any other sizes, not an ELSEIF.

[rsines]

Thanks, I didn't catch that last else if!

But what I want is to use the same background image on several pages (re-sized for screen resolution). If I can find away of doing it I wouldn't have to make as many pages and use a page re-direct script based on the users screen resolution.

I tried this, and it doesn't work either:

<script language="JavaScript1.2">
<!--
if (screen.width==800||screen.height==600)
  if (document.all||document.getElementById)
  document.body.style.background="url('bkg_sm.gif') white center no-repeat fixed"

else if (screen.width==1024||screen.height==768)
  if (document.all||document.getElementById)
  document.body.style.background="url('bkg_md.gif') white center no-repeat fixed"

else
if (document.all||document.getElementById)
document.body.style.background="url("bkg_lg.gif")  white center no-repeat fixed"
//-->
</script>