Until a more formal FoxyCart + Squarespace instruction set is done, this page will link to relevant posts and information about using FoxyCart with Squarespace.
In order to use the foxycart thickbox overlay on your Squarespace site, you will need to add the foxycart code into the head of your Squarespace pages, the same as you would for any other site. (This is taken directly from How to Setup Your Site)
<!-- BEGIN FOXYCART FILES --> <script src="https://YOURDOMAIN.foxycart.com/files/foxycart_includes.js" type="text/javascript" charset="utf-8"></script> <link rel="stylesheet" href="https://YOURDOMAIN.foxycart.com/files/foxybox.css" type="text/css" media="screen" charset="utf-8" /> <!-- END FOXYCART FILES -->
If you'd like to use the default theme, you'll need one additional file. This is to style the elements of the foxybox that are not in the iframe (specifically, the close and the continue shopping links).
<!-- BEGIN FOXYCART FILES --> <link rel="stylesheet" href="https://YOURDOMAIN.foxycart.com/themes/standard/theme.foxybox.css" type="text/css" media="screen" charset="utf-8" /> <!-- END FOXYCART FILES -->
One way to add this code to your Squarespace site is:
That's it!
Now, you can insert cart links and forms on any of your Squarespace HTML pages using the “code insert” cog button in the Squarespace HTML page editor.