bacoords

<?php
// Put this in wp-config.php and replace https://example.com/ with the URL of the production site.
define( 'BC_USE_REMOTE_MEDIA_URL', 'https://example.com' );

// Put the rest of this in functions.php or a custom plugin or somewhere else.
if ( defined( 'BC_USE_REMOTE_MEDIA_URL' ) && ! empty( BC_USE_REMOTE_MEDIA_URL ) ) {
	add_filter( 'wp_get_attachment_image_src', 'bc_filter_wp_get_attachment_image_src' );
	add_filter( 'wp_calculate_image_srcset', 'bc_filter_wp_calculate_image_srcset' );
	add_filter( 'wp_get_attachment_url', 'bc_filter_wp_get_attachment_url' );
}

paulirish

/* bling.js */
window.$ = document.querySelector.bind(document);
window.$$ = document.querySelectorAll.bind(document);
Node.prototype.on = window.on = function(name, fn) { this.addEventListener(name, fn); };
NodeList.prototype.__proto__ = Array.prototype;
NodeList.prototype.on = function(name, fn) { this.forEach((elem) => elem.on(name, fn)); };

aprea

-- delete any usermeta specific to the other subsites
delete from wp_usermeta where meta_key regexp '^wp_([0-9]+)_';

-- duplicate the wp_usermeta structure in a working data table,
-- but add a unique index for filtering out duplicates
create table _fix_usermeta like wp_usermeta;
alter table _fix_usermeta add unique(user_id, meta_key);

-- copy the site-specific usermeta, keeping only the last of each duplicate
insert into _fix_usermeta

luetkemj

// This gist is now maintained on github at https://github.com/luetkemj/wp-query-ref

<?php
/**
* WordPress Query Comprehensive Reference
* Compiled by luetkemj - luetkemj.github.io
*
* CODEX: http://codex.wordpress.org/Class_Reference/WP_Query#Parameters
* Source: https://core.trac.wordpress.org/browser/tags/4.9.4/src/wp-includes/query.php
*/