The bestest way to change the jQuery version in WordPress

mu-new-jquery.php

<?php

/**
 * Attention all WordPress developers.
 * NEVER EVER EVER DO THIS:
 wp_deregister_script('jquery');
 * AND I DO MEAN NEVER!!!!!
 * Any plugin that has dependency on jQuery registered like 
 wp_register_script( 'a-script', .., .., deps: [ 'jquery ' ], ..);
 * will now BREAK!!!!
 * instead, do this:
*/

add_action('wp_head', function(){ // just in time (~PHP_INT_MAX === PHP_INT_MIN, a.k.a., firstest.)
  global $wp_scripts;
  $version = '3.4.1'; // the required jQuery version, check cdnjs for actually available.
  $wp_scripts->registered['jquery-core']->ver = $version;
  $wp_scripts->registered['jquery-core']->src = 'https://cdnjs.cloudflare.com/ajax/libs/jquery/'. $version .'/jquery.min.js';
}, ~PHP_INT_MAX);

note.txt

just in case you think I made a typo:

bestest: absolute best
firstest: absolute first