Dave’s WordPress Live Search adds “live search” functionality to your WordPress site. As visitors type words into your WordPress site’s search box, the plugin continually queries WordPress, looking for search results that match what the user has typed so far.
The live search technique means that most people will find the results they are looking for before they finish typing their query, and it saves them the step of having to click a submit button to get their search results.
This plugin can recognize when it’s being used with WP e-Commerce and offer an option to search store products instead of posts/pages.
It also works with the Relevanssi plugin which enhances search results.
Requires PHP 5.0 or higher.