Scripting – Aja Lapus

I’ve been playing around with JavaScript once when I’ve encountered a problem about my scripts not working, especially those attached to event handlers. You could probably see JavaScript declarations like this on a script or another:

window.onload = functionName;

And, soon, I found out that a lot of plugins I have use the same declaration for initializing their scripts. So, I looked for references and realized that they overwrite one another by declaring that assignment operation over and over again. Looking for solutions, I came across two possible ways to do it:

if (typeof window.onload != 'function') {
	window.onload = newOnLoadFn;
} else {
	var onLoadStack = window.onload;
	window.onload = function() {
		onLoadStack();
		newOnLoadFn();
	}
}

var onLoadStack = window.onload;
window.onload = function() {
	if (typeof onLoadStack == 'function' && onLoadStack) {
		onLoadStack();
	}
	newOnLoadFn();
}

Coding preferences applies, as either basically does the same effect of stacking window.onload events. You could put them on a function if you must:

function addOnLoadEvent(newOnLoadFn) {
	if (typeof window.onload != 'function') {
		window.onload = newOnLoadFn;
	} else {
		var onLoadStack = window.onload;
		window.onload = function() {
			onLoadStack();
			newOnLoadFn();
		}
	}
}

And call events using:

addOnLoadEvent(
	// declaration of function type
);

I would recommend anyone distributing scripts to make use of this to avoid conflicts with other event-triggered scripts users may have beside yours. Thanks!

Category: Scripting

Stacking Script Event Loaders