Question: I'm working on a codebase with multiple blocks of code setting some behavior on document.ready() (jQuery). Is there a way to enforce that one specific block is called before any of the others? 

Background:
I need to detect JS errors in an automated testing environment, so I need the code that starts logging JS errors to execute before any other JS code executes.

Answer: 
As @jfriend00 mention that `ready callbacks are called in the order they were registered.`

So even if this code block called on the beginning, you can set another callback in it so it'll be executed on endmost.

```js
jQuery(document).ready(function(){
    jQuery(document).ready(function(){
        // This block will be executed after all ready calls.
    });
});

```
I was trying to do something similar, I was loading a bunch of polyfills that had .ready() functions, but I also had my own .ready()s on page that I needed executed first, though the polyfills were loaded in the header.

I found a nice way around it by having a .ready() very early on (right after jQuery loads) that executes functions from an array. Because it's very early in the source code it's .ready() is executed first. Further down the page I can add functions to the array and, so they all execute before any other .ready()s.

I've wrapped it up in a .beforeReady() function and put it on GitHub as jQuery-Before-Ready for anyone that is interested. 
<https://github.com/aim12340/jQuery-Before-Ready>