Vladimir Prelovac

The Yahoo! Exceptional Performance team recommends <a href="http://developer.yahoo.com/performance/rules.html#js_bottom" rel="nofollow ugc">placing scripts at the bottom of your page</a> because of the way browsers download components.
“The problem caused by scripts is that they block parallel downloads. The HTTP/1.1 specification suggests that browsers download no more than two components in parallel per hostname. If you serve your images from multiple hostnames, you can get more than two downloads to occur in parallel. While a script is downloading, however, the browser won’t start any other downloads, even on different hostnames.
In some situations it’s not easy to move scripts to the bottom. If, for example, the script uses document.write to insert part of the page’s content, it can’t be moved lower in the page. There might also be scoping issues. In many cases, there are ways to workaround these situations.”
WordPress default behavior is to load javascript in the page.
This plugin will move all javascript code to the footer if the plugins have <a href="http://www.prelovac.com/vladimir/best-practice-for-adding-javascript-code-to-wordpress-plugin" rel="nofollow ugc">declared javascript properly</a>.
Plugin by <a href="http://www.prelovac.com/vladimir" rel="nofollow ugc">Vladimir Prelovac</a>. Looking for <a href="http://www.prelovac.com/vladimir/services" rel="nofollow ugc">WordPress Services</a>?
<h3>License</h3>
This file is part of Footer JavaScript.
Footer JavaScript is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Footer JavaScript is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Footer JavaScript. If not, see <a href="http://www.gnu.org/licenses/" rel="nofollow ugc">http://www.gnu.org/licenses/</a>.

JavaScript to Footer

I used and face some of bad experience with it 

Can't give perfect result

This plugin automatically moves JavaScript code to page footer, speeding up page loading time.

Otto Kekäläinen

Viljami Kuosmanen

This plugin is useful if you have want to enable your users to insert custom CSS or add custom headers or some JavaScript into the site without having to edit any theme files. Unlike similar header/footer plugins, this plugin by design does not allow to insert PHP code and does not contain any evil eval() calls.
The plugin is safe to use in WordPress Network installations, where site admins are not supposed to have PHP execution access but any HTML/CSS/JS code is safe to accept.
Simple Header Footer HTML is made by Seravo.com. Seravo provides Premium Hosting and Upkeep service for WordPress.
Contributing
Source available at https://github.com/Seravo/wp-simple-header-footer-html

Simple Header Footer HTML

A simple plugin for injecting HTML into various places in your WordPress theme output.

JavaScript to Footer vs Simple Header Footer HTML