seajs主要做了2件事
1.定义什么是模块，如何声明模块:id、deps、factory、exports ----define=function(id,deps,factory){return exports}
2.管理模块依赖，解决自动加载。本质其实是个加载器loader：id配上路径规则,factory可以提取依赖模块，递归遍历后自动加载js文件
核心的代码是util-path.js和module.js
发现seajs已经修订到3.0.0部分实现有改动，有些地方随手写的，也没求证过估计误人子弟不少。忙着review下，后面再补了3、0版的module.js注释贻笑大方
对外接口
seajs.use 执行的入口方法
define 模块定义的初始化方法
seajs.use("a")->Module.get("a") m.load();执行fetch后加载define调用Module.save跟新deps m.onload(); m.exec(); 子模块： deps->Module.get() fetch/load 通知回调-> 主模板onload 模块状态：fetch--Module.fetch 拉取模板saved--Module.saved 拉取模板成功后就save模块（define会提取deps）loading--m.load() 检测依赖模块是否全部加载loaded--m.onload() 已加载全部模块后触发executing/executed-m.exec() seajs.use->mod.onload->mod.callback()->mod.exec(); use是seajs模块入口函数定义模块： Module.use(seajs.use)
Module.define(global.define)
核心类：Module
静态方法
Module.use(使用模块load后exec)、Module.preload(获取data.preload参数后执行Module.use)、Module.get(拿到模块,若无则创建)
模块use的执行过程
load 开始加载目标主模块
get 创建主模块
fetch 发送request请求加载模块,加载成功后执行define方法会抽取依赖deps
save 加载成功后会执行define方法，解析依赖的deps。且保持Module.save
load 每次模块加载成功后onRequest回调主模块load判断是否remain==0,调用主模块onload(新版改用Module.prototype.pass)。每次子模板加载成功后，都要通知依赖自己的主模板。更新状态以便判断是否进入onload
onload 全部加载完触发onload，回调callback(seajs.use(id,callback))。只有主模板会有onload执行
exec 执行模块factory(即define(fn)的fn)，且将require关键字映射exec上，依次执行所有依赖模块
/* 创建seajs对象，标识版本号。创建data数据对象，data挂在seajs为外部访问*/var seajs = global.seajs = { // The current version of Sea.js being used version: "@VERSION"}var data = seajs.data = {}/* seajs自己的事件触发，on绑定事件，off移除，emit触发*//** * util-events.js - The minimal events support */var events = data.events = {}// Bind eventseajs.on = function(name, callback) { var list = events[name] || (events[name] = []) list.push(callback) return seajs}// Remove event. If `callback` is undefined, remove all callbacks for the// event. If `event` and `callback` are both undefined, remove all callbacks// for all eventsseajs.off = function(name, callback) { // Remove *all* events if (!(name || callback)) { events = data.events = {} return seajs } var list = events[name] if (list) { if (callback) { for (var i = list.length - 1; i >= 0; i--) { if (list[i] === callback) { list.splice(i, 1) } } } else { delete events[name] } } return seajs}// Emit event, firing all bound callbacks. Callbacks are passed the same// arguments as `emit` is, apart from the event namevar emit = seajs.emit = function(name, data) { var list = events[name], fn if (list) { // Copy callback lists to prevent modification list = list.slice() // Execute event callbacks while ((fn = list.shift())) { fn(data) } } return seajs}/* 类型判断和计数函数*//** * util-lang.js - The minimal language enhancement */function isType(type) { return function(obj) { return Object.prototype.toString.call(obj) === "[object " + type + "]" }}var isObject = isType("Object")var isString = isType("String")var isArray = Array.isArray || isType("Array")var isFunction = isType("Function")var _cid = 0function cid() { return _cid++}/* 解析路径的处理方法，包括： dirname 获取路径的目录 realpath 过滤目录中的./ ../ normalize 补全文件名.js后缀 parseAlias 解析配置别名 parsePaths 解析配置中的path parseVars 解析配置中{} parseMap 加载路径根据配置匹配规则映射 addBase 通过id，路由规则生成完整绝对路径 id2Uri 根据id获取uri，完整的绝对路径 loaderDir seajs文件路径的获取：根据id=seajsnode查找seajs的dom，获取src后匹配目录*//** * util-path.js - The utilities for operating path such as id, uri */var DIRNAME_RE = /[^?#]*\//var DOT_RE = /\/\.\//gvar DOUBLE_DOT_RE = /\/[^/]+\/\.\.\//// Extract the directory portion of a path// dirname("a/b/c.js?t=123#xx/zz") ==> "a/b/"// ref: http://jsperf.com/regex-vs-split/2function dirname(path) { return path.match(DIRNAME_RE)[0]}// Canonicalize a path// realpath("http://test.com/a//./b/../c") ==> "http://test.com/a/c"function realpath(path) { // /a/b/./c/./d ==> /a/b/c/d path = path.replace(DOT_RE, "/") // a/b/c/../../d ==> a/b/../d ==> a/d while (path.match(DOUBLE_DOT_RE)) { path = path.replace(DOUBLE_DOT_RE, "/") } return path}// Normalize an id// normalize("path/to/a") ==> "path/to/a.js"// NOTICE: substring is faster than negative slice and RegExpfunction normalize(path) { var last = path.length - 1 // If the uri ends with `#`, just return it without '#' if (path.charAt(last) === "#") { return path.substring(0, last) } return (path.substring(last - 2) === ".js" || path.indexOf("?") > 0 || path.substring(last - 3) === ".css") ? path : path + ".js"}var PATHS_RE = /^([^/:]+)(\/.+)$/var VARS_RE = /{([^{]+)}/gfunction parseAlias(id) { var alias = data.alias return alias && isString(alias[id]) ? alias[id] : id}function parsePaths(id) { var paths = data.paths var m if (paths && (m = id.match(PATHS_RE)) && isString(paths[m[1]])) { id = paths[m[1]] + m[2] } return id}function parseVars(id) { var vars = data.vars if (vars && id.indexOf("{") > -1) { id = id.replace(VARS_RE, function(m, key) { return isString(vars[key]) ? vars[key] : m }) } return id}function parseMap(uri) { var map = data.map var ret = uri if (map) { for (var i = 0, len = map.length; i < len; i++) { var rule = map[i] ret = isFunction(rule) ? (rule(uri) || uri) : uri.replace(rule[0], rule[1]) // Only apply the first matched rule if (ret !== uri) break } } return ret}var ABSOLUTE_RE = /^\/\/.|:\//var ROOT_DIR_RE = /^.*?\/\/.*?\//function addBase(id, refUri) { var ret var first = id.charAt(0) // Absolute if (ABSOLUTE_RE.test(id)) { ret = id } // Relative else if (first === ".") { ret = realpath((refUri ? dirname(refUri) : data.cwd) + id) } // Root else if (first === "/") { var m = data.cwd.match(ROOT_DIR_RE) ret = m ? m[0] + id.substring(1) : id } // Top-level else { ret = data.base + id } return ret}function id2Uri(id, refUri) { if (!id) return "" id = parseAlias(id) id = parsePaths(id) id = parseVars(id) id = normalize(id) var uri = addBase(id, refUri) uri = parseMap(uri) return uri}var doc = documentvar loc = locationvar cwd = dirname(loc.href)var scripts = doc.getElementsByTagName("script")// Recommend to add `seajsnode` id for the `sea.js` script elementvar loaderScript = doc.getElementById("seajsnode") || scripts[scripts.length - 1]// When `sea.js` is inline, set loaderDir to current working directoryvar loaderDir = dirname(getScriptAbsoluteSrc(loaderScript) || cwd)function getScriptAbsoluteSrc(node) { return node.hasAttribute ? // non-IE6/7 node.src : // see http://msdn.microsoft.com/en-us/library/ms536429(VS.85).aspx node.getAttribute("src", 4)}/* request 动态加载css或者script到head 创建dom原生link、script标签 addOnload 定义浏览器兼容的异步请求回调 getCurrentScript 获取当前资源加载状态为进行中interactive的资源*//** * util-request.js - The utilities for requesting script and style files * ref: tests/research/load-js-css/test.html */var head = doc.getElementsByTagName("head")[0] || doc.documentElementvar baseElement = head.getElementsByTagName("base")[0]var IS_CSS_RE = /\.css(?:\?|$)/ivar READY_STATE_RE = /^(?:loaded|complete|undefined)$/var currentlyAddingScriptvar interactiveScript// `onload` event is supported in WebKit < 535.23 and Firefox < 9.0// ref:// - https://bugs.webkit.org/show_activity.cgi?id=38995// - https://bugzilla.mozilla.org/show_bug.cgi?id=185236// - https://developer.mozilla.org/en/HTML/Element/link#Stylesheet_load_eventsvar isOldWebKit = (navigator.userAgent .replace(/.*AppleWebKit\/(\d+)\..*/, "$1")) * 1 < 536function request(url, callback, charset) { var isCSS = IS_CSS_RE.test(url) var node = doc.createElement(isCSS ? "link" : "script") if (charset) { var cs = isFunction(charset) ? charset(url) : charset if (cs) { node.charset = cs } } addOnload(node, callback, isCSS) if (isCSS) { node.rel = "stylesheet" node.href = url } else { node.async = true node.src = url } // For some cache cases in IE 6-8, the script executes IMMEDIATELY after // the end of the insert execution, so use `currentlyAddingScript` to // hold current node, for deriving url in `define` call currentlyAddingScript = node // ref: #185 & http://dev.jquery.com/ticket/2709 baseElement ? head.insertBefore(node, baseElement) : head.appendChild(node) currentlyAddingScript = null}function addOnload(node, callback, isCSS) { var missingOnload = isCSS && (isOldWebKit || !("onload" in node)) // for Old WebKit and Old Firefox if (missingOnload) { setTimeout(function() { pollCss(node, callback) }, 1) // Begin after node insertion return } node.onload = node.onerror = node.onreadystatechange = function() { if (READY_STATE_RE.test(node.readyState)) { // Ensure only run once and handle memory leak in IE node.onload = node.onerror = node.onreadystatechange = null // Remove the script to reduce memory leak if (!isCSS && !data.debug) { head.removeChild(node) } // Dereference the node node = null callback() } }}function pollCss(node, callback) { var sheet = node.sheet var isLoaded // for WebKit < 536 if (isOldWebKit) { if (sheet) { isLoaded = true } } // for Firefox < 9.0 else if (sheet) { try { if (sheet.cssRules) { isLoaded = true } } catch (ex) { // The value of `ex.name` is changed from "NS_ERROR_DOM_SECURITY_ERR" // to "SecurityError" since Firefox 13.0. But Firefox is less than 9.0 // in here, So it is ok to just rely on "NS_ERROR_DOM_SECURITY_ERR" if (ex.name === "NS_ERROR_DOM_SECURITY_ERR") { isLoaded = true } } } setTimeout(function() { if (isLoaded) { // Place callback here to give time for style rendering callback() } else { pollCss(node, callback) } }, 20)}function getCurrentScript() { if (currentlyAddingScript) { return currentlyAddingScript } // For IE6-9 browsers, the script onload event may not fire right // after the the script is evaluated. Kris Zyp found that it // could query the script nodes and the one that is in "interactive" // mode indicates the current script // ref: http://goo.gl/JHfFW if (interactiveScript && interactiveScript.readyState === "interactive") { return interactiveScript } var scripts = head.getElementsByTagName("script") for (var i = scripts.length - 1; i >= 0; i--) { var script = scripts[i] if (script.readyState === "interactive") { interactiveScript = script return interactiveScript } }}/** * module.js - The core of module loader *///系统全局对象，用来保存全局数据和状态var cachedMods = seajs.cache = {}var anonymousMetavar fetchingList = {}var fetchedList = {}var callbackList = {}var STATUS = Module.STATUS = { // 1 - The `module.uri` is being fetched FETCHING: 1, // 2 - The meta data has been saved to cachedMods SAVED: 2, // 3 - The `module.dependencies` are being loaded LOADING: 3, // 4 - The module are ready to execute LOADED: 4, // 5 - The module is being executed EXECUTING: 5, // 6 - The `module.exports` is available EXECUTED: 6}//模块类 id、deps、exports 构造函数function Module(uri, deps) { this.uri = uri this.dependencies = deps || [] this.exports = null this.status = 0//模块状态 // The number of unloaded dependencies this._remain = 0 // Who depend on me this._waitings = {}}//Module静态方法，Module.use使用模块，Module.preload调用data.preload后回调Module.use// Load preload modules before all other modulesModule.preload = function(callback) { var preloadMods = data.preload var len = preloadMods.length if (len) { Module.use(preloadMods, function() { // Remove the loaded preload modules preloadMods.splice(0, len) // Allow preload modules to add new preload modules Module.preload(callback) }, data.cwd + "_preload_" + cid()) } else { callback() }}//入口模块，ids--依赖模块，uri模块id：获取uri模块// Use function is equal to load a anonymous moduleModule.use = function (ids, callback, uri) { var mod = Module.get(uri, isArray(ids) ? ids : [ids]) mod.callback = function() { var exports = [] var uris = mod.resolve() for (var i = 0, len = uris.length; i < len; i++) { exports[i] = cachedMods[uris[i]].exec() } if (callback) { callback.apply(global, exports) } delete mod.callback } mod.load()}//获取uri模块，若cachedMods中无则创建个新模块Module.get = function(uri, deps) { return cachedMods[uri] || (cachedMods[uri] = new Module(uri, deps))}// seajs.use 入口方法// 执行过程：A依赖B,B依赖C，seajs.use(A):/*fetch 获取A模块的依赖模块(B),B拉取成功后回调A.load(每次依赖的文件onRquest，要跟新自己的状态)load 遍历A模块依赖的所有模块状态（B/C），直到remain==0，触发onloadonload 当A模块所有依赖都已加载，触发A.callbackexec seajs.use 将执行模块的callback设置为exec，调用A.exec,且A模块中的require映射了exec方法，链式的执行下去。。*/seajs.use = function(ids, callback) { Module.preload(function() { Module.use(ids, callback, data.cwd + "_use_" + cid()) }) return seajs}//将依赖的模块通过fetch方法注册，最终执行load请求js，onRequest回调onload// Load module.dependencies and fire onload when all doneModule.prototype.load = function() { var mod = this // If the module is being loaded, just wait it onload call if (mod.status >= STATUS.LOADING) { return } mod.status = STATUS.LOADING // Emit `load` event for plugins such as combo plugin var uris = mod.resolve()//获取依赖uris emit("load", uris) var len = mod._remain = uris.length var m // Initialize modules and register waitings 拿到依赖模块注册依赖 for (var i = 0; i < len; i++) { m = Module.get(uris[i])//获取依赖module if (m.status < STATUS.LOADED) { //模块未加载 // Maybe duplicate m._waitings[mod.uri] = (m._waitings[mod.uri] || 0) + 1//记录下有几个模块依赖自己 } else { mod._remain--//加载后-- } } //若所有依赖都加载后，执行onload if (mod._remain === 0) { mod.onload() return } // Begin parallel loading var requestCache = {} for (i = 0; i < len; i++) { m = cachedMods[uris[i]] if (m.status < STATUS.FETCHING) { m.fetch(requestCache) } else if (m.status === STATUS.SAVED) { m.load() } } // Send all requests at last to avoid cache bug in IE6-9. Issues#808 for (var requestUri in requestCache) { if (requestCache.hasOwnProperty(requestUri)) { requestCache[requestUri]() } }}//将模块的所有依赖的uri都注册到此模块的requestCache列表中// Fetch a moduleModule.prototype.fetch = function(requestCache) { var mod = this var uri = mod.uri mod.status = STATUS.FETCHING // Emit `fetch` event for plugins such as combo plugin var emitData = { uri: uri } emit("fetch", emitData) var requestUri = emitData.requestUri || uri // Empty uri or a non-CMD module if (!requestUri || fetchedList[requestUri]) { mod.load() return } if (fetchingList[requestUri]) { callbackList[requestUri].push(mod) return } fetchingList[requestUri] = true callbackList[requestUri] = [mod] // Emit `request` event for plugins such as text plugin emit("request", emitData = { uri: uri, requestUri: requestUri, onRequest: onRequest, charset: data.charset }) if (!emitData.requested) { requestCache ? requestCache[emitData.requestUri] = sendRequest : sendRequest() } function sendRequest() { request(emitData.requestUri, emitData.onRequest, emitData.charset) } function onRequest() { delete fetchingList[requestUri] fetchedList[requestUri] = true // Save meta data of anonymous module if (anonymousMeta) { save(uri, anonymousMeta) anonymousMeta = null } // Call callbacks var m, mods = callbackList[requestUri] delete callbackList[requestUri] while ((m = mods.shift())) m.load() }}//若模块的依赖加载全部加载触发onload回调mod.callback，同时通知所有依赖他的模块// Call this method when module is loadedModule.prototype.onload = function() { var mod = this mod.status = STATUS.LOADED if (mod.callback) { mod.callback() } // Notify waiting modules to fire onload var waitings = mod._waitings var uri, m for (uri in waitings) { if (waitings.hasOwnProperty(uri)) { m = cachedMods[uri] m._remain -= waitings[uri] if (m._remain === 0) { m.onload() } } } // Reduce memory taken delete mod._waitings delete mod._remain}//解析模块依赖的uris 获取绝对uris// Resolve module.dependenciesModule.prototype.resolve = function() { var mod = this var ids = mod.dependencies var uris = [] for (var i = 0, len = ids.length; i < len; i++) { uris[i] = resolve(ids[i], mod.uri) } return uris}//触发resolve事件，返回id2Uri// Helpersfunction resolve(id, refUri) { // Emit `resolve` event for plugins such as text plugin var emitData = { id: id, refUri: refUri } emit("resolve", emitData) return emitData.uri || id2Uri(emitData.id, refUri)}//加载完所有依赖的模块后，执行自身模块，同时通过关键字require将依赖的模块顺序执行// Execute a moduleModule.prototype.exec = function () { var mod = this // When module is executed, DO NOT execute it again. When module // is being executed, just return `module.exports` too, for avoiding // circularly calling if (mod.status >= STATUS.EXECUTING) { return mod.exports//模块已执行 } mod.status = STATUS.EXECUTING // Create require var uri = mod.uri //执行require的id function require(id) { return cachedMods[require.resolve(id)].exec() } //获得id模块的绝对路径 require.resolve = function(id) { return resolve(id, uri) } //异步请求uri require.async = function(ids, callback) { Module.use(ids, callback, uri + "_async_" + cid()) return require } // Exec factory var factory = mod.factory var exports = isFunction(factory) ? factory(require, mod.exports = {}, mod) : factory if (exports === undefined) { exports = mod.exports } // Emit `error` event if (exports === null && !IS_CSS_RE.test(uri)) { emit("error", mod) } // Reduce memory leak delete mod.factory mod.exports = exports mod.status = STATUS.EXECUTED // Emit `exec` event emit("exec", mod) return exports}//对外的接口 define(function(){...})用于定义模块，初始化模块的基础属性(并不执行模块factory方法)Module.define.cmd = {}global.define = Module.define// Define a moduleModule.define = function (id, deps, factory) { var argsLen = arguments.length // define(factory) if (argsLen === 1) { factory = id id = undefined } else if (argsLen === 2) { factory = deps // define(deps, factory) if (isArray(id)) { deps = id id = undefined } // define(id, factory) else { deps = undefined } } // Parse dependencies according to the module factory code if (!isArray(deps) && isFunction(factory)) { deps = parseDependencies(factory.toString()) } var meta = { id: id, uri: resolve(id), deps: deps, factory: factory } // Try to derive uri in IE6-9 for anonymous modules if (!meta.uri && doc.attachEvent) { var script = getCurrentScript() if (script) { meta.uri = script.src } // NOTE: If the id-deriving methods above is failed, then falls back // to use onload event to get the uri } // Emit `define` event, used in nocache plugin, seajs node version etc emit("define", meta) meta.uri ? save(meta.uri, meta) : // Save information for "saving" work in the script onload event anonymousMeta = meta}function save(uri, meta) { var mod = Module.get(uri) // Do NOT override already saved modules if (mod.status < STATUS.SAVED) { mod.id = meta.id || uri mod.dependencies = meta.deps || [] mod.factory = meta.factory mod.status = STATUS.SAVED }}// For Developers 调试接口seajs.Module = Moduledata.fetchedList = fetchedListdata.cid = cid//获取模块idseajs.resolve = id2Uri//获取模块exports接口seajs.require = function(id) { return (cachedMods[resolve(id)] || {}).exports}
附commonjs、seajs、requirejs比较
#commonjs 与seajs
* commonjs ：node的编写规范，为运行在服务器端的非浏览器环境的模块系统定义。模块间的依赖通过require同步加载，导致浏览器端无法采用这种设计
* seajs：将commonjs的规范扩展后，可以在浏览器环境下运行的模式系统设计规范。通过define(function(){});
详细说明：
#requirejs 与seajs
requirejs是amd规范，seajs是cmd规范
：
RequireJS 和 SeaJS 区别： ，执行define的延迟
补充Sea.js 3.0.0 module.js注释
function Module(uri, deps) { this.uri = uri this.dependencies = deps || [] this.status = 0 this._entry = []}//获取模板的全路径// Resolve id to uriModule.resolve = function(id, refUri) { // Emit `resolve` event for plugins such as text plugin var emitData = { id: id, refUri: refUri } emit("resolve", emitData) return emitData.uri || seajs.resolve(emitData.id, refUri)}//定义一个模块mod// Define a moduleModule.define = function (id, deps, factory) { var argsLen = arguments.length // define(factory) if (argsLen === 1) { factory = id id = undefined } else if (argsLen === 2) { factory = deps // define(deps, factory) if (isArray(id)) { deps = id id = undefined } // define(id, factory) else { deps = undefined } } // Parse dependencies according to the module factory code if (!isArray(deps) && isFunction(factory)) { deps = parseDependencies(factory.toString()) } var meta = { id: id, uri: Module.resolve(id), deps: deps, factory: factory } // Try to derive uri in IE6-9 for anonymous modules if (!meta.uri && doc.attachEvent) { var script = getCurrentScript() if (script) { meta.uri = script.src } // NOTE: If the id-deriving methods above is failed, then falls back // to use onload event to get the uri } // Emit `define` event, used in nocache plugin, seajs node version etc emit("define", meta) meta.uri ? Module.save(meta.uri, meta) : // Save information for "saving" work in the script onload event anonymousMeta = meta}//生成mod，赋值一些基本属性// Save meta data to cachedModsModule.save = function(uri, meta) { var mod = Module.get(uri) // Do NOT override already saved modules if (mod.status < STATUS.SAVED) { mod.id = meta.id || uri mod.dependencies = meta.deps || [] mod.factory = meta.factory mod.status = STATUS.SAVED emit("save", mod) }}//创建mod，缓存到cachedMods// Get an existed module or create a new oneModule.get = function(uri, deps) { return cachedMods[uri] || (cachedMods[uri] = new Module(uri, deps))}//load执行一个匿名module// Use function is equal to load a anonymous moduleModule.use = function (ids, callback, uri) { var mod = Module.get(uri, isArray(ids) ? ids : [ids]) mod._entry.push(mod) mod.history = {} mod.remain = 1 mod.callback = function() { var exports = [] var uris = mod.resolve() for (var i = 0, len = uris.length; i < len; i++) { exports[i] = cachedMods[uris[i]].exec() } if (callback) { callback.apply(global, exports) } delete mod.callback delete mod.history delete mod.remain delete mod._entry } mod.load()}/************************************************************* 对外只暴露 Module.use(seajs.use) Module.define(global.define) ************************************************************///获得mod的所有dep的uri // Resolve module.dependenciesModule.prototype.resolve = function() { var mod = this var ids = mod.dependencies var uris = [] for (var i = 0, len = ids.length; i < len; i++) { uris[i] = Module.resolve(ids[i], mod.uri) } return uris}//递归遍历自身依赖的子模板，判断全部加载完毕后执行onload// Load module.dependencies and fire onload when all doneModule.prototype.load = function() { var mod = this // If the module is being loaded, just wait it onload call if (mod.status >= STATUS.LOADING) { return } mod.status = STATUS.LOADING // Emit `load` event for plugins such as combo plugin var uris = mod.resolve() emit("load", uris) //将依赖uri遍历，判断是否全部加载 // Pass entry to it's dependencies mod.pass(uris) //如果全部加载，执行onload // If module has entries not be passed, call onload if (mod._entry.length) { mod.onload() return } // Begin parallel loading var requestCache = {} var m //对依赖的模板执行拉取，拉取后执行load递归子依赖 for (var i = 0, len = uris.length; i < len; i++) { m = cachedMods[uris[i]] if (m.status < STATUS.FETCHING) { m.fetch(requestCache) } //若模板已经拉取过，跳过拉取执行load else if (m.status === STATUS.SAVED) { m.load() } } // Send all requests at last to avoid cache bug in IE6-9. Issues#808 for (var requestUri in requestCache) { if (requestCache.hasOwnProperty(requestUri)) { requestCache[requestUri]() } }}//将依赖uri遍历，判断是否全部加载Module.prototype.pass = function(uris) { var mod = this uris = uris || mod.resolve() var len = uris.length //use时mod._entry.push(mod) for (var i = 0; i < mod._entry.length; i++) { var entry = mod._entry[i] var count = 0 for (var j = 0; j < len; j++) { var m = Module.get(uris[j]) // If the module is unload and unused in the entry, pass entry to it if (m.status < STATUS.LOADED && !entry.history.hasOwnProperty(m.uri)) { entry.history[m.uri] = true count++ m._entry.push(entry) if(m.status === STATUS.LOADING) { m.pass() } } } // If has passed the entry to it's dependencies, modify the entry's count and del it in the module if (count > 0) { entry.remain += count - 1 mod._entry.shift() i-- } }}//拉取模板，成功拉取后save并通知依赖自己的模板更新load// Fetch a moduleModule.prototype.fetch = function(requestCache) { var mod = this var uri = mod.uri mod.status = STATUS.FETCHING // Emit `fetch` event for plugins such as combo plugin var emitData = { uri: uri } emit("fetch", emitData) var requestUri = emitData.requestUri || uri // Empty uri or a non-CMD module if (!requestUri || fetchedList.hasOwnProperty(requestUri)) { mod.load() return } if (fetchingList.hasOwnProperty(requestUri)) { callbackList[requestUri].push(mod) return } fetchingList[requestUri] = true callbackList[requestUri] = [mod] // Emit `request` event for plugins such as text plugin emit("request", emitData = { uri: uri, requestUri: requestUri, onRequest: onRequest, charset: data.charset }) if (!emitData.requested) { requestCache ? requestCache[emitData.requestUri] = sendRequest : sendRequest() } function sendRequest() { seajs.request(emitData.requestUri, emitData.onRequest, emitData.charset) } function onRequest(error) { delete fetchingList[requestUri] fetchedList[requestUri] = true // Save meta data of anonymous module if (anonymousMeta) { Module.save(uri, anonymousMeta) anonymousMeta = null } // Call callbacks var m, mods = callbackList[requestUri] delete callbackList[requestUri] while ((m = mods.shift())) { // When 404 occurs, the params error will be true if(error === true) { m.error() } else { m.load() } } }}//全部加载完触发onload，回调callback(seajs.use(id,callback))// Call this method when module is loadedModule.prototype.onload = function() { var mod = this mod.status = STATUS.LOADED for (var i = 0, len = mod._entry.length; i < len; i++) { var entry = mod._entry[i] if (--entry.remain === 0) { entry.callback() } } delete mod._entry}//seajs.use->mod.onload->mod.callback()->mod.exec();// Execute a moduleModule.prototype.exec = function () { var mod = this // When module is executed, DO NOT execute it again. When module // is being executed, just return `module.exports` too, for avoiding // circularly calling if (mod.status >= STATUS.EXECUTING) { return mod.exports } mod.status = STATUS.EXECUTING if (mod._entry && !mod._entry.length) { delete mod._entry } //non-cmd module has no property factory and exports if (!mod.hasOwnProperty('factory')) { mod.non = true return } // Create require var uri = mod.uri function require(id) { var m = Module.get(require.resolve(id)) if (m.status == STATUS.ERROR) { throw new Error('module was broken: ' + m.uri); } return m.exec() } require.resolve = function(id) { return Module.resolve(id, uri) } require.async = function(ids, callback) { Module.use(ids, callback, uri + "_async_" + cid()) return require } // Exec factory var factory = mod.factory var exports = isFunction(factory) ? factory(require, mod.exports = {}, mod) : factory if (exports === undefined) { exports = mod.exports } // Reduce memory leak delete mod.factory mod.exports = exports mod.status = STATUS.EXECUTED // Emit `exec` event emit("exec", mod) return exports}