Defer parsing of javascript to improve performance in wordpress

Nothing for introduction, hehe! A very small snippet which will help you to defer parsing all javascript files except jquery in wordpress. Here is the code:
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<?php | |
function defer_parsing_of_js ( $url ) { | |
if ( FALSE === strpos( $url, '.js' ) ) return $url; | |
if ( strpos( $url, 'jquery.js' ) ) return $url; | |
return "$url' defer "; | |
} | |
add_filter( 'clean_url', 'defer_parsing_of_js', 11, 1 ); |
You can add those codes in your functions.php in the theme, if you think your theme won’t be changed. Otherwise mu-plugins is the best solution. To use mu-plugins, go to /wp-content/ and find the folder with name ‘mu-plugins’. If there is no folder in that name, then create a folder, name it ‘mu-plugins’, create a file inside that, give any name you like and paste the code in there. You don’t need to activate that plugin. Mu-plugins means must use plugins, so it will be activated automatically always. If you use mu-plugins then add a php start tag at the beginning of the code.