Nick Haskins

WP Live Search (beta) is a search plugin for WordPress that returns results as the user types for what they are looking. It currently supports posts, pages, post types, including multiple post types, and design modes.
This is very much a working prototype, so please log any issues you find on the Github repo below. 
<a href="https://github.com/bearded-avenger/wp-live-search" rel="nofollow ugc">https://github.com/bearded-avenger/wp-live-search</a>
Here’s some documentation. 
<a href="http://bearded-avenger.github.io/wp-live-search/" rel="nofollow ugc">http://bearded-avenger.github.io/wp-live-search/</a>
Add the shortcode <code>[wp_live_search]</code> to a page or something. There’s a few shortcode attributes that you can use, and are as follows:
type=”” 
Your choices are <code>posts</code> or <code>pages</code>. Defaults to <code>posts</code>. You can also pass <code>type,type</code> to search multiple post types. For example type=”recipes,books”
multi=”” 
By default this is turned off. Set this to true only if you’re using multiple post types above.
placeholder=”” 
The text displayed in the input. Defaults to <code>Search...</code>.
number=”” 
Total search result to return. Default is 20
excerpt=”true” 
Show the excerpt along with the title and featured image (if set)
compact=”true” 
Makes a tiny WP Live Search for use in header widgets and such
dropdown=”true” 
Display search results as a drop-down instead of pushing down the content around it
results=”” 
The text displayed for the results. Defaults to <code>entries found</code>.
results_style=”inside” 
Displays the “entries found” inside of the input area, useful for using in areas like header widgets where space is minimal.
target=”” 
An optional target UL parent to send the search results to. Example <code>target="#someotherdiv"</code>.
Here are a couple examples:
Default Usage: 
 [wp_live_search]
Use in Header Widget: 
 [wp_live_search compact=”true” dropdown=”true” results=”found” results_style=”inside”]
Search through multiple post types: 
 [wp_live_search multi=”true” type=”posts,page”]

WP Live Search

A super light-weight live search plugin that utilizes the WP REST API.

Dana Ross

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 <a href="http://ajaxpatterns.org/Live_Search" rel="nofollow ugc">live search</a> 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 functionality requires Javascript, but the search box still works normally if Javascript is not available.
http://www.youtube.com/watch?v=7CGR2bJ1mLM 
<a href="https://plugins.svn.wordpress.org/daves-wordpress-live-search/assets/intro_video_transcript.txt" rel="nofollow ugc">transcript</a>
This plugin is compatible with the <a href="https://wordpress.org/extend/plugins/xlanguage/" rel="ugc">xLanguage</a> and <a href="http://wpml.org/" rel="nofollow ugc">WPML</a> plugins for internationalization (i18n) of search results.
<h3>Filters</h3>
See <a href="https://plugins.svn.wordpress.org/daves-wordpress-live-search/trunk/filter_examples.php" rel="nofollow ugc">filter_examples.php</a> in 
the plugin files for examples of how to use these filters. Remember, these filters only affect the 
Dave’s WordPress Live Search display, not the normal WordPress search results or the posts themselves.
<ol>
<li>dwls_alter_results</li>
<li>dwls_attachment_thumbnail</li>
<li>dwls_post_title</li>
<li>dwls_the_excerpt</li>
<li>dwls_post_date</li>
<li>dwls_author_name</li>
<li>dwls_alter_result_template</li>
<li>dwls_post_custom</li>
<li>dwls_query_fields</li>
</ol>
<h3>Wish List</h3>
Features I want to implement in future releases:
<ol>
<li>“No results found” message (optional)</li>
</ol>

Dave's WordPress Live Search

At first, this seems like a good plugin and it is. I tried to report a bug a couple of months ago and, despite the fact the plugin says it's compatible with the latest version of WordPress, there seems to be bugs that are not addressed. At this point, I had to hack the plugin and edit source code to make it work.

Unmaintained plugin

You do a great job

Adds "live search" functionality to your WordPress site. Uses the built-in search and jQuery.

WP Live Search vs Dave's WordPress Live Search