Need javascript like adsense any help would be great!

Hey Everyone!

I need someone that can help me with some coding.

I have a code like this.

<SCRIPT language="JavaScript">
bg_color = "#FFFFFF";
</SCRIPT>
<SCRIPT TYPE="text/javascript" SRC="http://www2.domainname.com/file/file.js"></SCRIPT>

HTML:

I have scripts that people will be using on my website but I want people to be able to change the background colour to match their website.

So I thought a simple way would be using Javascript.

I just need the code that codes in the file.js to make the colour change when the value is changed in the code?

Can anyone help?

Thank you, Chris

 

document.write could help
may not be that easy.