源码注释
//Zepto.js//(c) - Thomas Fuchs//Zepto.js may be freely distributed under the MIT license.;(function($){var _zid = 1, undefined,slice = Array.prototype.slice,isFunction = $.isFunction,isString = function(obj){ return typeof obj == 'string' },handlers = {},//_zid: events 事件缓存池specialEvents={},focusinSupported = 'onfocusin' in window,//是否支持即将获取焦点时触发函数 onfocusin focus不支持冒泡focus = { focus: 'focusin', blur: 'focusout' }, //焦点修正hover = { mouseenter: 'mouseover', mouseleave: 'mouseout' } // mouseenter mouseleave不冒泡的修正 ，mouseover mouseout功能一样且支持冒泡//此处标准浏览器，click、mousedown、mouseup、mousemove抛出的就是MouseEvents，应该也是对低版本IE等某些浏览器的修正specialEvents.click = specialEvents.mousedown = specialEvents.mouseup = specialEvents.mousemove = 'MouseEvents'/*** 取元素标识符，没有设置一个返回* @param element* @returns {*|number}*/function zid(element) {return element._zid || (element._zid = _zid++)}/*** 查找元素上事件响应函数集合* @param element* @param event* @param fn* @param selector* @returns {Array}*/function findHandlers(element, event, fn, selector) {//解析命名空间事件名event = parse(event)// if (event.ns) var matcher = matcherFor(event.ns)//找到响应函数集合return (handlers[zid(element)] || []).filter(function(handler) {return handler&& (!event.e || handler.e == event.e) //判断事件类型是否相同&& (!event.ns || matcher.test(handler.ns)) //判断事件命名空间是否相同 RegExp.prototype.test = function(String) {};&& (!fn || zid(handler.fn) === zid(fn)) // zid(handler.fn)返回handler.fn的标识，没有加一个，判断fn标识符是否相同&& (!selector || handler.sel == selector) //返回 handler， 判断selector是否相同 })}/*** 解析事件类型* @param event 'click'* @returns {{e: * 事件类型 , ns: string 命名空间}}*/function parse(event) {//如果有.分隔，证明有命名空间var parts = ('' + event).split('.')return {e: parts[0], ns: parts.slice(1).sort().join(' ')}}/*** 生成命名空间的正则对象* @param ns* @returns {RegExp}*/function matcherFor(ns) {return new RegExp('(?:^| )' + ns.replace(' ', ' .* ?') + '(?: |$)')}/*** 事件捕获* 对focus和blur事件且浏览器不支持focusin focusout，通过设置捕获来模拟冒泡* @param handler* @param captureSetting* @returns {*|boolean|boolean}*/function eventCapture(handler, captureSetting) {//如果是focus和blur事件且浏览器不支持focusin focusout时，//设置为可捕获，间接达到冒泡的目的return handler.del &&(!focusinSupported && (handler.e in focus)) ||!!captureSetting}/*** 修正事件类型 focus->focusIn blur->focusOut mouseenter->mouseover mouseleave->mouseout* @param type 事件类型* @returns {*|boolean|*|*}*/function realEvent(type) {//hover[type] mouseenter和mouseleave 转换成 mouseover和mouseout// focus[type] focus blur 修正为 focusin focusoutreturn hover[type] || (focusinSupported && focus[type]) || type}/*** 增加事件底层方法* @param element* @param events 字符串 如‘click'* @param fn* @param data* @param selector* @param delegator* @param capture*/function add(element, events, fn, data, selector, delegator, capture){//zid Zepto会在elemnt上扩展一个标识属性_zid// 读取元素上已绑定的事件处理函数var id = zid(element), set = (handlers[id] || (handlers[id] = []))// \s 匹配空格events.split(/\s/).forEach(function(event){//如果是ready事件if (event == 'ready') return $(document).ready(fn)//解析事件 {e: * 事件类型 , ns: string 命名空间}var handler = parse(event)//保存fn,下面为了处理mouseenter, mouseleave时，对fn进行了修改//存储fn响应函数//存储selectorhandler.fn = fnhandler.sel = selector// emulate mouseenter, mouseleave// 模仿 mouseenter, mouseleave//如果事件是mouseenter, mouseleave，模拟mouseover mouseout事件处理if (handler.e in hover) fn = function(e){//relatedTarget 事件属性返回与事件的目标节点相关的节点。// 对于 mouseover 事件来说，该属性是鼠标指针移到目标节点上时所离开的那个节点。// 对于 mouseout 事件来说，该属性是离开目标时，鼠标指针进入的节点。// 对于其他类型的事件来说，这个属性没有用。var related = e.relatedTarget//不存在，表明不是mouseover、mouseout事件，//related !== this && !$.contains(this, related)) 当related不在事件对象event内 表示事件已触发完成，不是在move过程中，需要执行响应函数if (!related || (related !== this && !$.contains(this, related)))//执行响应函数return handler.fn.apply(this, arguments)}//事件委托handler.del = delegatorvar callback = delegator || fnhandler.proxy = function(e){//修正evente = compatible(e)//如果是阻止所有事件触发if (e.isImmediatePropagationStopped()) returne.data = data //缓存数据//执行回调函数，context：element，arguments：event,e._args(默认是undefind，trigger()时传递的参数）var result = callback.apply(element, e._args == undefined ? [e] : [e].concat(e._args))//当事件响应函数返回false时，阻止浏览器默认操作和冒泡if (result === false) e.preventDefault(), e.stopPropagation()return result}//设置事件响应函数的索引,删除事件时，根据它来删除 delete handlers[id][handler.i]handler.i = set.length//缓存到handlers[id]里 set = handlers[id]set.push(handler)//元素支持DOM2级事件绑定if ('addEventListener' in element)//绑定事件//DOM源码// @param {string} type// @param {EventListener|Function} listener// @param {boolean} [useCapture]是否使用捕捉，默认 false// EventTarget.prototype.addEventListener = function(type,listener,useCapture) {};//realEvent(handler.e) 修正后的事件类型//handler.proxy 修正为代理上下文的事件响应函数// eventCapture(handler, capture) element.addEventListener(realEvent(handler.e), handler.proxy, eventCapture(handler, capture))})}/*** 删除事件, 对应add* @param element* @param events* @param fn* @param selector* @param capture 是否捕获*/function remove(element, events, fn, selector, capture){var id = zid(element) //找到元素标识;(events || '').split(/\s/).forEach(function(event){ //events多个以空格分隔//遍历事件响应函数集合findHandlers(element, event, fn, selector).forEach(function(handler){delete handlers[id][handler.i]//删除缓存在handlers的响应函数if ('removeEventListener' in element)//调用DOM原生方法删除事件//DOM源代码///**// @param {string} type// @param {EventListener|Function} listener// @param {boolean} [useCapture]// *///EventTarget.prototype.removeEventListener = function(type,listener,useCapture) {};//realEvent(handler.e) 修正事件类型handler.proxy 代理的事件响应函数eventCapture(handler, capture)修正的是否捕获//与增加事件底层函数 add最后一行 element.addEventListener(realEvent(handler.e), handler.proxy, eventCapture(handler, capture)) 呼应 element.removeEventListener(realEvent(handler.e), handler.proxy, eventCapture(handler, capture))})})}//此处不清楚要干嘛，将事件两个核心底层方法封装到event对象里，方便做Zepto插件事件扩展？$.event = { add: add, remove: remove }/*** 代理* (function,context),(context,name)* @param fn* @param context* @returns {*}*/$.proxy = function(fn, context) {var args = (2 in arguments) && slice.call(arguments, 2) //如果传了第3个参数，取到第3个参数以后（包含第3个参数）所有的参数数组，挺好的判断技巧if (isFunction(fn)) { //fn是函数//采用闭包，以context调用函数。// args.concat(slice.call(arguments)) 将传参挪到前面 如传递给$.proxy(fn,context,3,4); 转变成 fn.apply(context,[3,4,fn,context,3,4])var proxyFn = function(){ return fn.apply(context, args ? args.concat(slice.call(arguments)) : arguments) }// 标记函数proxyFn._zid = zid(fn)return proxyFn} else if (isString(context)) { //context是字符串, 实际传参(context,name)if (args) { //修正传参，再以$.proxy调用args.unshift(fn[context], fn) // unshift 往数组开头添加新的项return $.proxy.apply(null, args)} else {return $.proxy(fn[context], fn)}} else {throw new TypeError("expected function") //抛出异常:要求的函数类型错误 }}/*** 绑定事件,应直接采用on* 源自1.9版本前jquery的绑定事件的区分：bind()是直接绑定在元素上.live()则是通过冒泡的方式来绑定到元素上的。更适合列表类型的，绑定到document DOM节点上。和.bind()的优势是支持动态数据。.delegate()则是更精确的小范围使用事件代理，性能优于.live().on()则是1.9版本整合了之前的三种方式的新事件绑定机制* @param event* @param data* @param callback* @returns {*}*/$.fn.bind = function(event, data, callback){return this.on(event, data, callback)}/*** 解绑事件,应直接用off* @param event* @param callback* @returns {*}*/$.fn.unbind = function(event, callback){return this.off(event, callback)}/*** 绑定一次性事件* @param event* @param selector* @param data* @param callback* @returns {*}*/$.fn.one = function(event, selector, data, callback){return this.on(event, selector, data, callback, 1)}var returnTrue = function(){return true},returnFalse = function(){return false},ignoreProperties = /^([A-Z]|returnValue$|layer[XY]$)/,//匹配 大写字母A-Z开头/returnValue/layerX/layerY用于createProxy(),过滤event对象的属性eventMethods = {preventDefault: 'isDefaultPrevented',//是否已调用preventDefault() preventDefault阻止浏览器的默认动作stopImmediatePropagation: 'isImmediatePropagationStopped', //是否已调用stopImmediatePropagation()，stopImmediatePropagation DOM3提出的阻止任何事件触发stopPropagation: 'isPropagationStopped' //是否已调用stopPropagation() stopPropagation阻止冒泡}/*** 修正event对象* @param event 代理的event对象 原生event对象* @param source 原生event对象* @returns {*}*/function compatible(event, source) {//event.isDefaultPrevented 是否已调用了preventDefault方法////event是代理事件对象时，赋值给sourceif (source || !event.isDefaultPrevented) {source || (source = event)//遍历，代理preventDefault stopImmediatePropagation stopPropagation等方法$.each(eventMethods, function(name, predicate) {var sourceMethod = source[name]event[name] = function(){//扩展event对象，代理preventDefault stopImmediatePropagation stopPropagation方法 ，兼容浏览器不支持，同时做其他事情this[predicate] = returnTrue//如果执行了3方法，原生事件对象isDefaultPrevented isImmediatePropagationStopped isPropagationStopped 三方法标记truereturn sourceMethod && sourceMethod.apply(source, arguments) //且调用原生方法 }event[predicate] = returnFalse //扩展原生事件对象 isDefaultPrevented isImmediatePropagationStopped isPropagationStopped三方法，默认返回false。})//如果浏览器支持 defaultPrevented DOM3 EVENT提出的能否取消默认行为if (source.defaultPrevented !== undefined ? source.defaultPrevented :'returnValue' in source ? source.returnValue === false :source.getPreventDefault && source.getPreventDefault())event.isDefaultPrevented = returnTrue //默认可以取消 }//返回修正对象return event}/*** 创建事件代理* @param event Event对象* @returns {*}*/function createProxy(event) {var key, proxy = { originalEvent: event } //存储原始eventfor (key in event)//复制event属性至proxy，ignoreProperties里包含的属性除外if (!ignoreProperties.test(key) && event[key] !== undefined) proxy[key] = event[key]// return compatible(proxy, event)}/*** 小范围冒泡绑定事件,应直接采用on*/$.fn.delegate = function(selector, event, callback){return this.on(event, selector, callback)}/*** 解绑事件,应直接用off*/$.fn.undelegate = function(selector, event, callback){return this.off(event, selector, callback)}/*** 冒泡到document.body绑定事件,应直接采用on* @param event* @param callback* @returns {*}*/$.fn.live = function(event, callback){$(document.body).delegate(this.selector, event, callback)return this}/*** 在doument.body解绑事件,应直接用off*/$.fn.die = function(event, callback){$(document.body).undelegate(this.selector, event, callback)return this}/*** 扩展Zepto on监听事件方法* 元素上绑定一个或多个事件的事件处理函数* 注意： 方法参数不应超过5个，超过5个，应该用arguments。5个是惯例。if或for或闭包嵌套层也不应超过5层* @param event 事件集 字符串/* @param selector 子选择器* @param data event.data* @param callback事件响应函数* @param one 内部用， $.fn.one用。标记一次性事件* @returns {*}*/$.fn.on = function(event, selector, data, callback, one){var autoRemove, delegator, $this = this//event是对象{click:fn},支持这种方式我觉得没多大用if (event && !isString(event)) {$.each(event, function(type, fn){$this.on(type, selector, data, fn, one)})return $this}//选择器非字符串 callback非方法//未传data on('click','.ss',function(){})if (!isString(selector) && !isFunction(callback) && callback !== false)callback = data, data = selector, selector = undefined//data传了function 或未传if (callback === undefined || data === false)callback = data, data = undefined//callback传了false，转换成false函数if (callback === false) callback = returnFalse//遍历元素，return $this.each(function(_, element){//如果是一次性，先删掉事件，再执行事件if (one) autoRemove = function(e){remove(element, e.type, callback)return callback.apply(this, arguments)}//传递了选择器if (selector) delegator = function(e){//以element元素为容器，以事件源为起点，往上冒泡找到匹配selector的元素// match 响应函数对应的事件源var evt, match = $(e.target).closest(selector, element).get(0)// selector能找到，且不是容器，即不是绑定事件的上下文，即$('.parent').on('click','.son',fn)形式。开始处理委托。if (match && match !== element) {//createProxy(e) 创建event代理对象 currentTarget指向selector元素，liveFired指向绑定事件的容器elementevt = $.extend(createProxy(e), {currentTarget: match, liveFired: element})//执行事件响应函数//autoRemove触发一次事件响应函数后自动销毁。 callback触发事件响应函数// [evt].concat(slice.call(arguments, 1))响应函数的参数数组return (autoRemove || callback).apply(match, [evt].concat(slice.call(arguments, 1)))}}add(element, event, callback, data, selector, delegator || autoRemove)})}/*** 移除事件响应函数* @param event* @param selector* @param callback* @returns {*}*/$.fn.off = function(event, selector, callback){var $this = this//是对象，遍历移除if (event && !isString(event)) {$.each(event, function(type, fn){$this.off(type, selector, fn)})return $this}// 是函数if (!isString(selector) && !isFunction(callback) && callback !== false)callback = selector, selector = undefinedif (callback === false) callback = returnFalsereturn $this.each(function(){//元素遍历移除remove(this, event, callback, selector)})}/*** 触发事件* @param event 事件类型* @param args* @returns {*}*/$.fn.trigger = function(event, args){//修正event为事件对象event = (isString(event) || $.isPlainObject(event)) ? $.Event(event) : compatible(event)//传参event._args = argsreturn this.each(function(){// handle focus(), blur() by calling them directly//如果事件是focus blurif (event.type in focus && typeof this[event.type] == "function") this[event.type]()// items in the collection might not be DOM elements// 支持浏览器原生触发事件API//DOM源码// /**// @param {Event} event// @return {boolean}// */// EventTarget.prototype.dispatchEvent = function(event) {};else if ('dispatchEvent' in this) this.dispatchEvent(event)//模拟触发事件else $(this).triggerHandler(event, args)})}// triggers event handlers on current element just as if an event occurred,// doesn't trigger an actual event, doesn't bubble/*** 触发事件，不能冒泡* @param event event对象* @param args 传参* @returns {*}*/$.fn.triggerHandler = function(event, args){var e, resultthis.each(function(i, element){//修正事件对象e = createProxy(isString(event) ? $.Event(event) : event)e._args = argse.target = element//找到此元素上此事件类型上的事件响应函数集，遍历，触发$.each(findHandlers(element, event.type || event), function(i, handler){//调用 handler.proxy执行事件result = handler.proxy(e)//如果event调用了immediatePropagationStopped()，终止后续事件的响应if (e.isImmediatePropagationStopped()) return false})})return result}// shortcut methods for `.bind(event, fn)` for each event type/*** 给常用事件生成便捷方法* @param event* @param args* @returns {*}*/;('focusin focusout focus blur load resize scroll unload click dblclick '+'mousedown mouseup mousemove mouseover mouseout mouseenter mouseleave '+'change select keydown keypress keyup error').split(' ').forEach(function(event) {$.fn[event] = function(callback) {return (0 in arguments) ?//有callback回调，是绑定事件，否则，触发事件 ，// 不用on？on才通用啊 ,bind也是调用on//$.fn.bind = function(event, data, callback){// return this.on(event, data, callback)// }this.bind(event, callback) :this.trigger(event)}})/*** 创建Event对象* @param type* @param props 扩展到Event对象上的属性* @returns {*}* @constructor*/$.Event = function(type, props) {//当type是个对象时if (!isString(type)) props = type, type = props.type//对应 specialEvents.click = specialEvents.mousedown = specialEvents.mouseup = specialEvents.mousemove = 'MouseEvents'//创建event对象，如果是click,mousedown,mouseup mousemove，创建为MouseEvent对象,bubbles设为冒泡//TODO: 为什么要把这些事件单独拎出来？var event = document.createEvent(specialEvents[type] || 'Events'), bubbles = true// (name == 'bubbles') ? (bubbles = !!props[name])如果是冒泡，确保是true/false 浏览器只识别true、false， !!props[name]明确进行类型转换// event[name] = props[name] props属性扩展到event对象上if (props) for (var name in props) (name == 'bubbles') ? (bubbles = !!props[name]) : (event[name] = props[name])//初始化event对象，type为事件类型，如click，bubbles为是否冒泡，第三个参数表示是否可以用preventDefault方法来取消默认操作//初始化event对象，type：事件类型 如click bubbles能否 true: 能否使用preventDefault取消浏览器默认操作//附上DOM源码/*@browser Gecko@param {string} eventTypeArg@param {boolean} canBubbleArg@param {boolean} cancelableArg*///Event.prototype.initEvent = function(eventTypeArg,canBubbleArg,cancelableArg) {};event.initEvent(type, bubbles, true)//添加isDefaultPrevented方法，event.defaultPrevented返回一个布尔值,表明当前事件的默认动作是否被取消,也就是是否执行了 event.preventDefault()方法.return compatible(event)}})(Zepto)
三大核心方法on/off/trigger流程解析
浏览器原生支持自定义事件举例(Zepto自定义事件/浏览器事件原理)
var element = document.body; //绑定事件元素var handler = function(e,a,b){//事件响应函数alert('监听成功 a:' +a+' b:'+b +' e.data:'+ JSON.stringify(e.data));}//监听事件element.addEventListener('add',function(e){e.data = {wo:1}; //对监听事件进行传参handler.apply(element, e._args == undefined ? [e] : [e].concat(e._args));},false);//抛出自定义事件var addEvent = document.createEvent('Events');addEvent.initEvent('add',true,true);addEvent._args = [2,3]; //传参element.dispatchEvent(addEvent);
方法图
