官网提供的按需引入方法为全量按需引入,在打包分离中,仍旧存在使用不到的图表被打包进去。
例如:组件A使用了折线图、柱状图,组件B只用到了折线图,但是打包组件B的时候,柱状图也会被打包进去。
本文提供一种动态按需引入的思路,使得只用到折线图的组件B,打包的时候只打包折线图,不会将组件A用到[……]
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// 处理报错 ResizeObserver loop completed with undelivered notifications. export const handlerResizeObserverError = () => { const debounce = (callback: (...args: any[]) => void, delay: number) => { let tid: any; return function (...args: any[]) { const ctx = self; tid && clearTimeout(tid); tid = setTimeout(() => { callback.apply(ctx, args) }, delay) } } const _ = (window as any).ResizeObserver; (window as any).ResizeObserver = class ResizeObserver extends _ { constructor(callback: (...args: any[]) => void) { callback = debounce(callback, 20) super(callback) } } } |
访问者模式(Visitor Pattern)
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定义:使用一个访问者类,改变元素类的执行算法。通过这种方式,元素的执行算法可以随着访问者改变而改变。 目的:将数据结构与数据操作分离。 场景:您在朋友家做客,您是访问者,朋友接受您的访问,您通过朋友的描述,然后对朋友的描述做出一个判断,这就是访问者模式。 |
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// 元素类 class Elements { constructor () { this.action = () => { console.log('hi~') } this.accept = (visitor) => { visitor.visit(this) } } } // 访问者 class Visitor { constructor () { this.visit = (elements) => { elements.action() } } } const ele = new Elements() const visi = new Visitor() ele.accept(visi) |
解释器模式(Interpreter Pattern)
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定义:提供了评估语言的语法或表达式的方式。 目的:对于一些固定文法构建一个解释句子的解释器。 场景:编译器、运算表达式计算。 |
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// 定义对于语法的断言 class TerminalExpression { constructor (data) { this.data = data } interpret (context) { if (context.indexOf(this.data) > -1) { return true } return false } } // 添加表达式判断符 class OrExpression { constructor(expr1, expr2) { this.expr1 = expr1; this.expr2 = expr2; } interpret(context) { return this.expr1.interpret(context) || this.expr2.interpret(context); } } class AndExpression { constructor(expr1, expr2) { this.expr1 = expr1; this.expr2 = expr2; } interpret(context) { return this.expr1.interpret(context) && this.expr2.interpret(context); } } // 获取对应表达式 function getMaleExpression(){ const robert = new TerminalExpression("Robert"); const john = new TerminalExpression("John"); return new OrExpression(robert, john); } function getMarriedWomanExpression(){ const julie = new TerminalExpression("Julie"); const married = new TerminalExpression("Married"); return new AndExpression(julie, married); } // 判断语句断言 const isMale = getMaleExpression(); const isMarriedWoman = getMarriedWomanExpression(); console.log("John is male? " + isMale.interpret("John")); console.log("Julie is a married women? " ) |
中介者模式(Mediator Pattern)
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定义:用来降低多个对象和类之间的通信复杂性。 目的:用一个中介对象来封装一系列的对象交互,中介者使各对象不需要显式地相互引用,从而使其耦合松散,而且可以独立地改变它们之间的交互。 场景:MVC框架中的控制器C就是模型M和识图V的中介者。 |
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let mediator = (() => { let msg = {} return { register: (type, action) => { if (!msg[type]) msg[type] = [] msg[type].push(action) }, send: (type) => { if (msg[type]) { for (let i = 0; i < msg[type].length; i++) { msg[type][i] && msg[type][i]() } } } } })() mediator.register('demo', () => { console.log('first') }) mediator.register('demo', () => { console.log('second') }) mediator.send('demo') |
Github地址:https://github.com/skillnull/Design-Mode-Example[……]
职责链模式(Chain of Responsibility Pattern)
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定义:为请求创建了一个接收者对象的链。 目的:避免请求发送者与接收者耦合在一起,让多个对象都有可能接收请求,将这些对象连接成一条链,并且沿着这条链传递请求,直到有对象处理它为止。 场景:红楼梦中的"击鼓传花"。 |
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// 采购请求 let PurchaseRequest = (amount, productName) => { this.amount = amount this.productName = productName } // 处理方 let Approver = (name, nextApprover) => { this.name = name this.nextApprover = nextApprover } Approver.prototype.processRequest = () => { throw new Error() } // ConcreteHandler let Manager = (name, nextApprover) => { Approver.call(this, name, nextApprover) } extend(Manager, Approver) Manager.prototype.processRequest = (request) => { if (request.Amount < 10000.0) { console.log('ok') } else if (NextApprover != null) { this.nextApprover.ProcessRequest(request) } } // ConcreteHandler,副总 let VicePresident = function (name, nextApprover) { Approver.call(this, name, nextApprover) } extend(VicePresident, Approver); VicePresident.prototype.processRequest = function (request) { if (request.Amount < 25000.0) { console.log('ok'); } else if (NextApprover != null) { this.nextApprover.ProcessRequest(request) } } // ConcreteHandler,总经理 let President = function (name, nextApprover) { Approver.call(this, name, nextApprover) } extend(President, Approver) President.prototype.processRequest = function (request) { if (request.Amount < 100000.0) { console.log('ok') } else if (NextApprover != null) { this.nextApprover.ProcessRequest(request) } } let requestTelphone = new PurchaseRequest(4000.0, "Telphone") let requestSoftware = new PurchaseRequest(10000.0, "Visual Studio") let requestComputers = new PurchaseRequest(40000.0, "Computers") let manager = new Manager("LearningHard") let Vp = new VicePresident("Tony") let Pre = new President("BossTom") // 设置责任链 manager.NextApprover = Vp Vp.NextApprover = Pre // 处理请求 manager.ProcessRequest(requestTelphone) manager.ProcessRequest(requestSoftware) manager.ProcessRequest(requestComputers) |
命令模式(Command Pattern)
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定义:请求以命令的形式包裹在对象中,并传给调用对象。调用对象寻找可以处理该命令的合适的对象,并把该命令传给相应的对象,该对象执行命令。 目的:将一个请求封装成一个对象,从而使您可以用不同的请求对客户进行参数化。 场景:在一个快餐店,用户向服务员点餐。服务员将用户的需求记录在清单上。 |
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let dialog = { show () { console.log('show a dialog') } } let animation = { start () { console.log('show animation') } } let setCommand = (btn, cmd) => { btn.onclick = () => { cmd.run() } } class ShowDialogCommand { constructor (receiver) { this.receiver = receiver } run () { this.receiver.show() } } class StartAnimationCommand { constructor (receiver) { this.receiver = receiver } run () { this.receiver.start() } } setCommand(btn1, new ShowDialogCommand(dialog)) setCommand(btn2, new StartAnimationCommand(animation)) |