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javascript eval() - Invalid Argument

  • Sabu
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Post June 12th, 2004, 12:35 am

Ok guys, I've looked everywhere but I'm absolutely stuck.

If I use this:
Code: [ Select ]
<script language="JavaScript">
<!--
function setBlock(block, chimage, bgimage, chlink) {
eval("top." + block + ".style.backgroundImage='" + chimage + "'");
}

setBlock("a1", "man.gif", "beach.jpg", "link");
-->
</script>
  1. <script language="JavaScript">
  2. <!--
  3. function setBlock(block, chimage, bgimage, chlink) {
  4. eval("top." + block + ".style.backgroundImage='" + chimage + "'");
  5. }
  7. setBlock("a1", "man.gif", "beach.jpg", "link");
  8. -->
  9. </script>

it gives me 'invalid argument' for the eval function. However, if I remove the ' ' around chimage, like so

Code: [ Select ]
<script language="JavaScript">
<!--
function setBlock(block, chimage, bgimage, chlink) {
eval("top." + block + ".style.backgroundImage=" + chimage);
}

setBlock("a1", "man.gif", "beach.jpg", "link");
-->
</script>
  1. <script language="JavaScript">
  2. <!--
  3. function setBlock(block, chimage, bgimage, chlink) {
  4. eval("top." + block + ".style.backgroundImage=" + chimage);
  5. }
  7. setBlock("a1", "man.gif", "beach.jpg", "link");
  8. -->
  9. </script>


It gives me "'man' is undefined".

How can I write this to put the string chimage as the backgroundimage without messing up the eval function?

Extra notes:
This code is within an iframe, and the block 'a1' is a div outside of the iframe.
bgimage and chlink will be used later, but are not used for the purpose of this specific question. Obviously, once I do use them I'll use the same hints I get here
  • Anonymous
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Post June 12th, 2004, 12:35 am

  • RichB
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Post June 12th, 2004, 1:32 am

You just need to add url() for it to work in IE:

Code: [ Select ]
function setBlock(block, chimage, bgimage, chlink) {
eval("top." + block + ".style.backgroundImage='url(" + chimage + ")'");
}
  1. function setBlock(block, chimage, bgimage, chlink) {
  2. eval("top." + block + ".style.backgroundImage='url(" + chimage + ")'");
  3. }


For it to work in Mozilla/Firefox as well as IE I think you would need this:

Code: [ Select ]
function setBlock(block, chimage, bgimage, chlink) {
eval("top.document.getElementById('" + block + "').style.backgroundImage='url(" + chimage + ")'");
}
  1. function setBlock(block, chimage, bgimage, chlink) {
  2. eval("top.document.getElementById('" + block + "').style.backgroundImage='url(" + chimage + ")'");
  3. }


It might be easier to do it without the eval though:

Code: [ Select ]
function setBlock(block, chimage, bgimage, chlink) {
    var myDiv = top.document.getElementById(block);
    myDiv.style.backgroundImage='url(' + chimage + ')';
}
  1. function setBlock(block, chimage, bgimage, chlink) {
  2.     var myDiv = top.document.getElementById(block);
  3.     myDiv.style.backgroundImage='url(' + chimage + ')';
  4. }


Then you could reuse the myDiv reference without having to debug the evals.
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  • Sabu
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Post June 12th, 2004, 2:31 am

Double cool, working fantastically

thanks!

After experimenting for a good half an hour, I can't see how I was all that much different, but suddenly your second example works fine :crazyeyes:

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