Conditional Javascript and CSS plugin for Wordpress.

WP_Conditional_Script_Plugin.php

<?php
/*
Plugin Name: Conditional Javascript/ CSS
Plugin URI:  https://gist.github.com/nfreear
Description: 28 March 2014.
Author:  Nick Freear
Author URI:  https://github.com/nfreear
Version:  0.1
*/

/*
http://stackoverflow.com/questions/11564142/wordpress-enqueue-scripts-for-only-if-lt-ie-9
http://codex.wordpress.org/Function_Reference/wp_enqueue_script

<!--[if !IE]> --> This is not IE 5-9 <!-- <![endif]-->
*/

class Conditional_Script_Plugin {

  const REGEX = '@(\!?IE|(l|g)te? IE (7|8|9|10|11|12))@';
  const HELP_URL = 'http://quirksmode.org/css/condcom.html';


  public enqueue_conditional_script( $handle = 'html5shiv', $src = false, $cond = 'lt IE 9',
      $deps = array(), $ver = false, $in_footer = false, $debug = false ) {

    if (!preg_match(self::REGEX, $cond)) {
      if ($debug) {
        die("Syntax error in conditional comment. See, ". self::HELP_URL);
      }
      return false;
    }

    $src = $src ? $src : '//html5shim.googlecode.com/svn/trunk/html5.js';
    $cc_open = '<!--[if '. $cond .']>';
    $cc_close= '<![endif]-->';
    if ('!IE' == $cond) {
      $cc_open = '<!--[if !IE]>-->';
      $cc_close= '<!--<![endif]-->';
    }


    add_action( 'wp_head', function() {
      echo $cc_open .'<script src="'. $src .'"></script>'. $cc_close;
    } );
  }
  
}
$csp = new Conditional_Script_Plugin();