queue(),dequeue()

这两个方法,一个是往里面添加队列,一个是执行队列 也是分静态方法和实例方法,

同样,实例方法最后调用静态方法 源码主要分析一下延迟delay方法,如何起作用的,写的有点仓促,先记录一下

在这里参照了网络上的文章,给推荐一下,介绍的很详细了,作者比较用心:

http://www.html-js.com/card/1083,他是基于1.7的,我这边运行的是1.9的,但是核心思想是一样的

jQuery.extend({
	queue: function( elem, type, data ) {
		var queue;

		if ( elem ) {
			type = ( type || "fx" ) + "queue";
			queue = jQuery._data( elem, type );

			// Speed up dequeue by getting out quickly if this is just a lookup
			if ( data ) {
				if ( !queue || jQuery.isArray(data) ) {
					queue = jQuery._data( elem, type, jQuery.makeArray(data) );
				} else {
					queue.push( data );
				}
			}
			return queue || [];
		}
	},

	dequeue: function( elem, type ) {
		type = type || "fx";

		var queue = jQuery.queue( elem, type ),
			startLength = queue.length,
			fn = queue.shift(),
              //取出钩子对象,如果存在直接从cache中取,没有的话,新存入一个,并返回 hooks = jQuery._queueHooks( elem, type ),
              //写死的next函数,调用next()意味着执行dequeue一次 next = function() { jQuery.dequeue( elem, type ); }; // If the fx queue is dequeued, always remove the progress sentinel if ( fn === "inprogress" ) { fn = queue.shift(); startLength--; } hooks.cur = fn; if ( fn ) { // Add a progress sentinel to prevent the fx queue from being // automatically dequeued if ( type === "fx" ) { queue.unshift( "inprogress" ); } // clear up the last queue stop function delete hooks.stop;
              //重点说一下这里,elem域调用fn(queue的第一个函数),同时传递next函数(jQuery.dequeue( elem, type ))以及hooks
              //这个钩子对象平时没啥用就是清理key的时候调用empty返回的callback对象的fire方法,
              //第二个作用就是用在延迟定义里面,大家可以看一下下面的源码,它把这个钩子对象又添加了一个stop函数,意味着,这个队列可以清除定时的设置,清除之后,后面的就不执行了 fn.call( elem, next, hooks ); } if ( !startLength && hooks ) { hooks.empty.fire(); } }, // not intended for public consumption - generates a queueHooks object, or returns the current one _queueHooks: function( elem, type ) { var key = type + "queueHooks"; return jQuery._data( elem, key ) || jQuery._data( elem, key, {
              //这里利用了callbacks对象的add方法,将来fire的时候可以直接把elem元素中的这些key清除掉 empty: jQuery.Callbacks("once memory").add(function() { jQuery._removeData( elem, type + "queue" ); jQuery._removeData( elem, key ); }) }); } }); jQuery.fn.extend({ queue: function( type, data ) { var setter = 2;           // 如果遇到这样的参数: $().queue( function(){} );

          // 则重置下参数

		if ( typeof type !== "string" ) {
			data = type;
			type = "fx";
			setter--;
		}

		if ( arguments.length < setter ) {
			return jQuery.queue( this[0], type );
		}

		return data === undefined ?
			this :
			this.each(function() {
				var queue = jQuery.queue( this, type, data );

				// ensure a hooks for this queue
				jQuery._queueHooks( this, type );

				if ( type === "fx" && queue[0] !== "inprogress" ) {
					jQuery.dequeue( this, type );
				}
			});
	},
	dequeue: function( type ) {
		return this.each(function() {
			jQuery.dequeue( this, type );
		});
	},
	// Based off of the plugin by Clint Helfers, with permission.
	// http://blindsignals.com/index.php/2009/07/jquery-delay/
	delay: function( time, type ) {
		time = jQuery.fx ? jQuery.fx.speeds[ time ] || time : time;
		type = type || "fx";

		return this.queue( type, function( next, hooks ) {
			var timeout = setTimeout( next, time );
			hooks.stop = function() {
				clearTimeout( timeout );
			};
		});
	},
	clearQueue: function( type ) {
		return this.queue( type || "fx", [] );
	},
	// Get a promise resolved when queues of a certain type
	// are emptied (fx is the type by default)
	promise: function( type, obj ) {
		var tmp,
			count = 1,
			defer = jQuery.Deferred(),
			elements = this,
			i = this.length,
			resolve = function() {
				if ( !( --count ) ) {
					defer.resolveWith( elements, [ elements ] );
				}
			};

		if ( typeof type !== "string" ) {
			obj = type;
			type = undefined;
		}
		type = type || "fx";

		while( i-- ) {
			tmp = jQuery._data( elements[ i ], type + "queueHooks" );
			if ( tmp && tmp.empty ) {
				count++;
				tmp.empty.add( resolve );
			}
		}
		resolve();
		return defer.promise( obj );
	}
});

下面引用网络上的一个例子,大家有兴趣可以运行一下,主要对delay的理解

var obj = {};
			$.queue(obj, 'say', function(next) {
				document.write('hello ');
				next();
			});
			$.queue(obj, 'say', function() {
				document.write('world');
			});
			$.dequeue(obj, 'say');
			document.write("...............");
			var elem = {};
              //这里没用链式表达式本意是debug用的,这里的function传参也是参照dequeue中的fn.call( elem, next, hooks );这样就可以连着调用2次queue了 var e = $(elem).queue('handle', function(next) { document.write('first handle'); next(); }); e.delay("1000", 'handle'); e.queue('handle', function() { document.write('second handle'); }); e.dequeue('handle'); /* * dequeue中有一段话 var fn = queue.shift(); if ( fn ) { delete hooks.stop; fn.call( elem, next, hooks ); } 如果第一个函数是delay进去的函数的话,则赋予了elem.handleququeHooks.stop fn.call()这个函数把hooks传入,next原封不动,只是用setTimeout定时了 var next = function() { jQuery.dequeue( elem, type ); }; delay: function( time, type ) { time = jQuery.fx ? jQuery.fx.speeds[ time ] || time : time; type = type || "fx"; return this.queue( type, function( next, hooks ) { var timeout = setTimeout( next, time ); hooks.stop = function() { clearTimeout( timeout ); }; }); } * * * * */ var stopFn = $._data(elem, "handlequeueHooks").stop; // function () { clearTimeout( timeout ); } console.log(stopFn); // 停止运行 //stopFn(); // 手动运行后续处理函数 // 这里如果注释掉的话,第二个处理函数就不会执行, // 这里我们也看到了关于第二个参数: hooks 的使用方式。 //$(elem).dequeue('handle');

  

原文地址:https://www.cnblogs.com/aishangyizhihu/p/4249123.html