regen

This plugin compresses javascript files and CSS files loaded by the theme or other plugins automatically. 
Extra spaces, lines, and comments will be deleted. 
The compressor is based on <a href="http://code.google.com/p/jscsscomp/" rel="nofollow ugc">jscsscomp</a>.
<h4>Features</h4>
<ul>
<li>Auto-compression for the blog header.</li>
<li>Template tags which provide javascript compression.</li>
<li>You can turn on/off compressions in the admin page.</li>
<li>Editable CSS compression condition.</li>
<li>You can select where to output scripts.</li>
<li>You can exclude scripts from the compression if necessary.</li>
</ul>

Script Compressor

This plugin compresses javascript files and css files.

Steven Vachon

Combining HTML “minification” with cache and HTTP compression (<a href="https://wordpress.org/extend/plugins/wp-super-cache/" rel="ugc">WP Super Cache</a>, or similar) will cut down your bandwidth and ensure near-immediate content delivery while increasing your Google rankings.
This plugin will compress your HTML by shortening URLs and removing standard comments and whitespace; including new lines, carriage returns, tabs and excess spaces. Most importantly, by ignoring <code><pre></code>, <code><textarea></code>, <code><script></code> and Explorer® <code>conditional comment</code> tags, presentation will not be affected.

WP-HTML-Compression

Reduce file size by shortening URLs and safely removing all standard comments and unnecessary whitespace from an HTML document.

Script Compressor vs WP-HTML-Compression