最常用的10个javascript自定义函数

If there was ever a universal common.js shared among the entire develosphere, you’d fine these ten (plus one bonus) functions. It would be the swiss army knife no developer would go into production without. They have no doubt been tested tried and true and have proven usefulness and helpfulness to all those who’ve used them. So without further ado, here are what I believe to the top ten greatest custom JavaScript functions in use today.

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10) addEvent()

Surely a staple to event attachment! Regardless to what version you use written by whatever developer, it does what it says it does. And of course as you might of known, I’ve put together quite a handy version myself recently of addEvent() with some help from the contest winner and Mark Wubben along with a few minor syntax adjustments. But just to be fair to Scott Andrew, here is the original that started it all.

Scott Andrew’s original addEvent() function

function addEvent(elm, evType, fn, useCapture) {

	if (elm.addEventListener) {

		elm.addEventListener(evType, fn, useCapture);

		return true;

	}

	else if (elm.attachEvent) {

		var r = elm.attachEvent('on'   evType, fn);

		return r;

	}

	else {

		elm['on'   evType] = fn;

	}

}

9) addLoadEvent()

Originally written by Simon Willison and highly adopted by many others as a simple way to add events to trigger after the page has loaded. This of course attaches all your events to the onload event handler which some still see as necessary, nevertheless it does exactly what it’s supposed to, and does it well.

addLoadEvent() by Simon Willison

function addLoadEvent(func) {

	var oldonload = window.onload;

	if (typeof window.onload != 'function') {

		window.onload = func;

	}

	else {

		window.onload = function() {

			oldonload();

			func();

		}

	}

}

Of course another method is to simply assign multiple event listeners to the window by using addEvent() as described in number 10 as follows:

assigning multiple load events to window

addEvent(window,'load',func1,false);

addEvent(window,'load',func2,false);

addEvent(window,'load',func3,false);

8) getElementsByClass()

Originially written by nobody in particular. Several developers have implemented their own version and no one single version has proven to be better than another. As you might expect, my humble self has even had a crack at it. This function was spawned from developers needing a quick and elegant way of grabbing elements by a className and to a developer’s surprise, it’s not an original DOM method as one might think…afterall, we have getElementById, getElementsByName(), getElementsByTagName, what the hell happened to getElementsByClass??? Here it is in all its glory:

getElementsByClass by Dustin Diaz

function getElementsByClass(searchClass,node,tag) {

	var classElements = new Array();

	if ( node == null )

		node = document;

	if ( tag == null )

		tag = '*';

	var els = node.getElementsByTagName(tag);

	var elsLen = els.length;

	var pattern = new RegExp("(^|\s)" searchClass "(\s|$)");

	for (i = 0, j = 0; i < elsLen; i  ) {

		if ( pattern.test(els[i].className) ) {

			classElements[j] = els[i];

			j  ;

		}

	}

	return classElements;

}

Simply add a class name to the beginning of the funciton and the 2nd and 3rd arguments are optional and the magic is done for you!

7) cssQuery()

Originally written by Dean Edwards as a way to query the DOM according to CSS properties which supports a multitude of selectors. However in all fairness, this is more like a mini-library and not quite so light on the weight factor, but still, a very kick-ass function. Due to its length (and CC lisencing) I won’t post it on this site. Full documentation can be found on the myCssQuery reference and download page.

6) toggle()

To be totally honest, there are probably more variations of this function than there needs to be. The history of ‘toggling’ basically comes down to showing/hiding an element upon an event being fired. To make matters much simpler, I too have put one together. But by no means is it considered the ultimate toggle function, but it does do the basic functionality of showing and hiding.

toggle() by the masses

function toggle(obj) {

	var el = document.getElementById(obj);

	if ( el.style.display != 'none' ) {

		el.style.display = 'none';

	}

	else {

		el.style.display = '';

	}



}

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