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require.js
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require.js
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const requirejs = (() => {
const modules = window.modules = {}
document.addEventListener('moduleExported', function() {
;[...Object.values(modules)]
.filter(canDoModuleExports)
.forEach(doModuleExports)
})
function getRandomName() {
return `anonymous@${parseInt(Math.random() * 1000)}`
}
function resolveDependence(pathOrName) {
for (let key in modules) {
const module = modules[key]
if (module.moduleName === pathOrName) {
return module.modulePath
}
}
const path = pathOrName.endsWith('.js') ? pathOrName : pathOrName + '.js'
const a = document.createElement('a')
a.href = path
return a.href
}
function getCurrentScript() {
try {
return document.currentScript.src
} catch(e) {
return getRandomName()
}
}
function loadModule(src) {
if (src in modules) {
return
}
const script = document.createElement('script')
script.src = src
script.onload = () => {
modules[src].status = 'Loaded'
document.body.removeChild(script)
}
const module = {
status: 'Pending',
type: 'Sub',
modulePath: src,
}
modules[src] = module
document.body.appendChild(script)
module.status = 'Loading'
}
function loadExternalModule(dependencies, moduleName, modulePath, moduleFunction) {
modules[modulePath] = {
...modules[modulePath],
moduleName,
moduleFunction,
dependencies: dependencies.map(resolveDependence),
}
analyseModule(modules[modulePath])
}
function canDoModuleExports(module) {
if (module.status !== 'Loaded') {
return false
}
if (module.moduleExports !== null && typeof module.moduleExports !== 'undefined') {
return false
}
const dependencies = module.dependencies
if (typeof dependencies === 'undefined' || dependencies === null) {
return false
}
if (dependencies.length === 0) {
return true
}
for (let i = 0; i < dependencies.length; i++) {
const dependent = dependencies[i]
if (dependent in modules && modules[dependent].status === 'Exported') {
continue
} else {
return false
}
}
return true
}
function analyseModule(module) {
if (canDoModuleExports(module)) {
doModuleExports(module);
} else {
module.dependencies.forEach(loadModule)
}
}
function doModuleExports(module) {
const dependencies = module.dependencies
let args = null
if (dependencies.length === 0) {
args = []
} else {
args = dependencies.map(dependent => {
return modules[dependent].moduleExports
})
}
const moduleExports = module.moduleFunction.apply(null, args)
if (typeof moduleExports === 'undefined' || moduleExports === null) {
throw new Error(`Module ${module.moduleName} return (null | undefined), `)
}
module.moduleExports = moduleExports
module.status = 'Exported'
document.dispatchEvent(new Event("moduleExported"))
}
return {
getRandomName,
canDoModuleExports,
define(dependencies, moduleName, moduleFunction) {
const modulePath = getCurrentScript()
if (modulePath in modules) { // 这个模块是加载外部js得到的
setTimeout(() => { // 后置,让onload先执行
loadExternalModule(dependencies, moduleName, modulePath, moduleFunction)
})
return
}
const module = {
status: 'Loaded',
type: 'Main',
moduleName,
modulePath,
moduleFunction,
moduleExports: null,
dependencies: dependencies.map(resolveDependence),
}
modules[modulePath] = module
analyseModule(module)
}
}
})()
window.define = function(dependencies, moduleName, moduleFunction) {
if (typeof dependencies === 'function') {
requirejs.define([], requirejs.getRandomName(), dependencies)
return
}
if (typeof dependencies === 'string') {
requirejs.define([], dependencies, moduleName)
return
}
if (typeof moduleName === 'function') {
requirejs.define(dependencies, requirejs.getRandomName(), moduleName)
}
if (typeof moduleName === 'string') {
requirejs.define(dependencies, moduleName, moduleFunction)
}
}