create js file/code for other user to embed to use on their sites

I am creating a newsletter on my site, and after its completion I need to give a user a code to embed on their sites so they can directly show that pages on their sites. For this I am creating the HTML file f开发者_StackOverflow社区or the main newsletter pages, now the main problem for me is - how to create a JS script for it and give the code for embedding it to thier site.

Please give me some suggestions here

You just echo the required code such that it will be displayed in a textbox in the site. Customize the embed code as required using php.