Wordpress post editor crashes with Polyfill typo

Question

When trying to edit a wordpress post (page) the editor loads indefinitely, console shows JS error with post.php / polyfill, see code below. To me it seems to be a typo and I have no idea where the line is injected so I could change it manually.

Disabling all plugins did not change anything, neither did disabling Gutenberg. I am not much of a coder, nevertheless it seems to me there should not be a double quotation mark after the last 'defer"... in the line of code.

I am running WP 5.0.2 on Apache (Domainfactory) in a managed server environment, Theme is Enfold by Kriesi. Re-installing Wordpress and the theme (copied from working installations) changed nothing so far.

The reported error in the console is "Uncaught SyntaxError: missing ) after argument list" in https://.../wp-admin/post.php?post=23&action=edit&lang=de&classic-editor=1:238

There it says

( 'fetch' in window ) || document.write( '<script src="https://12345678-123.ch/wp-includes/js/dist/vendor/wp-polyfill-fetch.min.js?ver=3.0.0' defer='defer"></scr' + 'ipt>' );( document.contains ) || document.write( '<script src="https://12345678-123.ch/wp-includes/js/dist/vendor/wp-polyfill-node-contains.min.js?ver=3.26.0-0' defer='defer"></scr' + 'ipt>' );( window.FormData && window.FormData.prototype.keys ) || document.write( '<script src="https://12345678-123.ch/wp-includes/js/dist/vendor/wp-polyfill-formdata.min.js?ver=3.0.12' defer='defer"></scr' + 'ipt>' );( Element.prototype.matches && Element.prototype.closest ) || document.write( '<script src="https://12345678-123.ch/wp-includes/js/dist/vendor/wp-polyfill-element-closest.min.js?ver=2.0.2' defer='defer"></scr' + 'ipt>' );

Any idea would be much appreciated.

Answer 1

Here is an answer: WordPress v5.0.3 Gutenberg & JS error "Uncaught SyntaxError: missing ) after argument list"

The simplest way: Find & delete PHP Hook which added 'defer' to script (in the function.php file). Or if you have skills you can edit the code of the hook. Reason: Confusion/conflict with quotes (' & ") witch break down JS.

About 'defer' you can read here: https://www.w3schools.com/tags/att_script_defer.asp This is probably due to speed optimization on your website.

Answer 2

OK, so I struggled to find an answer myself to this - but this worked for me. I was stripping out the type='text/javascript' on script tags because it's not required for valid HTML5 - but WordPress insists on including it when you enqueue_script. I had a function in my theme like below to deal with this - so I just stopped it running in admin and it removed the error - your mileage may vary but maybe check your theme or plugins for something similar ;)

/**
 *
 * WordPress insists on inserting invalid javascript script tag definitions when enqueuing
 * This removes this cruft - to check in the future - will WordPress get patched to support this?
 *
 */
add_filter( 'script_loader_tag', 'mywfx_html5_clean_js_tags' );
function mywfx_html5_clean_js_tags( $input ) {

 if ( !is_admin() ) {

    $input = str_replace( "type='text/javascript' ", '', $input );
    return str_replace( "'", '"', $input );

 } else {

    return $input;

 }

}

Answer 3

Maybe the lesson to be learnt from injected code is: Check all potencial sources of code injection.

It turned out there was code put in the child themes' functions.php. At the time the question was asked it was as "unnessessary" to look for the problem there as it was dumb not to do that.

I am sorry and grateful for the help provided. Thank you.