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');