dojo/on/asyncEventListener.js

Dojo core is a powerful, lightweight library that makes common tasks quicker and easier. Animate elements, manipulate the DOM, and query with easy CSS syntax, all without sacrificing performance.

define(['../on', '../has', '../_base/window', 'dojo/has!host-browser?../dom-construct', 'dojo/has!host-browser?../domReady!'], function(on, has, baseWin, domConstruct){
	// summary:
	//		This sub module provide an event factory for delayed events (like debounce or throttle)
	// module:
	//		dojo/on/asyncEventListener


	//Testing is the browser support async event access
	//If not we need to clone the event, otherwise accessing the event properties
	//will trigger a JS error (invalid member)
	var testNode,
		testEvent,
		requiresClone = false;
	if(domConstruct) {
		testNode = domConstruct.create('input', {type: 'button'}, baseWin.body()),
		on.once(testNode, 'click', function(e){
			testEvent = e;
		});
		testNode.click();
		try{
			requiresClone = testEvent.clientX === undefined;
		}catch(e){
			requiresClone = true;
		}finally{
			domConstruct.destroy(testNode);
		}
	}
	has.add('native-async-event-support', !requiresClone);

	function clone(arg){
		// summary:
		//		clone the event
		// description:
		//		Used if the browser provides a corrupted event (comming from a node) when passed to an async function
		var argCopy = {},
			i;
		for(i in arg){
			argCopy[i] = arg[i];
		}
		return argCopy;
	}

	return function(listener){
		if(requiresClone){
			return function(e){
				//lang.clone fail to clone events, so we use a custom function
				listener.call(this, clone(e));
			};
		}
		return listener;
	};
});