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Fixed Render-blocking JQuery in WordPress with Autoptimize

rajeshroyal profile image Rajesh Royal Originally published at rajeshroyal.com on ・2 min read

Autoptimize by default excludes inline JS and jquery.js from optimization. Inline JS is excluded because it is a typical cache-buster (due to changing variables in it) and as inline JS often requires jQuery being available as a consequence that needs to be excluded as well.

The result of this “safe default” however is that jquery.js is a render-blocking resource. So even if you’re doing “inline & defer CSS” your Start-Render time (or one of the variations thereof) will be sub-optimal.

Jonas, the smart guy behind criticalcss.com, proposed to embed inline JS that requires jQuery in a function that executes after the DomContentLoaded event. And so I created a small code snippet as a proof of concept which hooks into Autoptimize’s API and that seems to work just fine;

Add below code to your themes function.php file. This code will replace all the $(document).ready() with Js native DOMContentLoaded event listener.


function ao_defer_inline_init() {
if ( get_option('autoptimize_js_include_inline') != 'on' ) {

function ao_defer_inline_jquery( $in ) {
if ( preg_match_all( '#<script.*>(.*)</script>#Usmi', $in, $matches, PREG_SET_ORDER ) ) {
foreach( $matches as $match ) {
if ( $match[1] !== '' && ( strpos( $match[1], 'jQuery' ) !== false || strpos( $match[1], '$' ) !== false ) ) {
// inline js that requires jquery, wrap deferring JS around it to defer it.
$new_match = 'var aoDeferInlineJQuery=function(){'.$match[1].'}; if (document.readyState === "loading") {document.addEventListener("DOMContentLoaded", aoDeferInlineJQuery);} else {aoDeferInlineJQuery();}';
$in = str_replace( $match[1], $new_match, $in );
} else if ( $match[1] === '' && strpos( $match[0], 'src=' ) !== false && strpos( $match[0], 'defer' ) === false ) {
// linked non-aggregated JS, defer it.
$new_match = str_replace( '<script ', '<script defer ', $match[0] );
$in = str_replace( $match[0], $new_match, $in );
return $in;

Now you can load jQuery defer or async on your site.
Your feedback is more than welcome.

original author: Gregor || Code from this Github gist


fix render blocking jquery in wordpress google page speed insight php code github gist

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Rajesh Royal


Designer, Front-end Developer, Traveller, Hooper. I design and code beautifully simple things, and I love what I do.


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