How to show a different product variation other than the default one on page load ( ajax trigger ) I have a node display for more than one product variation. Normally the user has to select one of the variation options by selecting them from the drop-down list which rebuilds the node display via AJAX.
Now say for instance that I want to link one of the product variations from else where. If I simply link www.example.com/node/10 the default product variation will be displayed which might not be the one I would like to present to the user.

So I probably have to send a query parameter in the URL, for example www.example.com/node/10?product_id=15, and trigger the AJAX event programmatically in my custom module.
Please see Implement unique URLs for particular products on product displays. 
It is an open feature request for Commerce, and it also links to a working sandbox with the implementation: http://drupal.org/sandbox/maciej.zgadzaj/1845182