How do you force your Javascript event to run first, regardless of the order in which the events were added?

Question

I have Javascript that people are including in their page. In my Javascript I have a version of jQuery (1.8 for sake of easy reference) that is sectioned off into its own n

Answer 1

Just so it's said, I think this might be possible if you override the native implementations of these functions. This is BAD practice - very bad practice when developing a library to alter native implementations, because it can easily conflict with other libraries.

However, for completeness, here's one possibility (completely untested, just demonstrating the general concept):

// override createElement()
var temp = document.createElement;
document.createElement = function() {
    // create element
    var el = document.createElement.original.apply(document, arguments);

    // override addEventListener()
    el.addEventListenerOriginal = el.addEventListener;
    el._my_stored_events = [];

    // add custom functions
    el.addEventListener = addEventListenerCustom;
    el.addEventListenerFirst = addEventListenerFirst;
    // ...
};
document.createElement.original = temp;

// define main event listeners
function myMainEventListeners(type) {
    if (myMainEventListeners.all[type] === undefined) {
        myMainEventListeners.all[type] = function() {
            for (var i = 0; i < this._my_stored_events.length; i++) {
                var event = this._my_stored_events[i];
                if (event.type == type) {
                    event.listener.apply(this, arguments);
                }
            }
        }
    }
    return myMainEventListeners.all[type];
}
myMainEventListeners.all = {};

// define functions to mess with the event list
function addEventListenerCustom(type, listener, useCapture, wantsUntrusted) {
    // register handler in personal storage list
    this._my_stored_events.push({
        'type' : type,
        'listener' : listener
    });

    // register custom event handler
    if (this.type === undefined) {
        this.type = myMainEventListeners(type);
    }
}

function addEventListenerFirst(type, listener) {
    // register handler in personal storage list
    this._my_stored_events.push({
        'type' : type,
        'listener' : listener
    });

    // register custom event handler
    if (this.type === undefined) {
        this.type = myMainEventListeners(type);
    }
}

// ...

A lot more work would need to be done in this regard to truly lock this down, and again, it's best not to modify native libraries. But it's a useful mental exercise that helps to demonstrate the flexibility JavaScript provides in solving problems like this.