Rishi Mehta

This plugin activate add to cart through ajax on varible product. By default woocommerce is not having this feature. Plugin is adding own jquery which is differ from woocommerce default add to cart jquery for simple product.
This plugin also supports sending additional field and other data added by other plugins. It will work with most of product addon and extra field data.
Let me know if you stumble upon any plugin conflict in support forum.

Woocommerce Ajax add to cart for variable products

This plugin activate add to cart through ajax on varible product.

R3dC0d3

This plugin allows woocommerce based stores to display a table with all the available variations on any given variable product on the product page. 
The table will react to what the customer selects on the attributes form.

Variations On Product Page

Allows you to display the available variations on the product page

Woocommerce Ajax add to cart for variable products vs Variations On Product Page