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//myAdd has the full function typelet myAdd = function(x: number, y: number): number {returnx +y; };//The parameters `x` and `y` have the type numberlet myAdd: (baseValue: number, increment: number) => number =function(x, y) {returnx + y; }; 这叫做“按上下文归类”,是类型...
function fn(name: string): string; function fn(age: number): number; function fn(nameorage: any): any { if (typeof nameorage == "string") { return "姓名:" + nameorage; } else if (typeof nameorage == "number") { return "年龄:" + nameorage } } // 姓名:张培跃 console.log(...
function getSecondParameter<T>(firstParameter: T): T { // 根据第一个参数的类型进行逻辑处理 // 返回第一个参数的类型作为第二个参数的类型 return firstParameter; } 在这个例子中,T是一个类型参数,它表示第一个参数的类型。函数的返回类型也是T,这意味着第二个参数的类型将与第一个参数的类型...
let myAdd2: (x: number, y: number) => number = function(x: number, y: number): number { return x + y } 1. 2. 3. 可选参数和默认参数 TypeScript 里的每个函数参数都是必须的。 这不是指不能传递 null 或 undefined 作为参数,而是说编译器检查用户是否为每个参数都传入了值。编译器还会假设...
public getAt: any; } export var optimizeBindingReferences: bool; } export module Namespace { export var define: any; export var defineWithParent: any; } export module Class { export function define(constructor: any, instanceMembers: any): any; export function derive( baseClass: any, construc...
When calling generic functions, TypeScript is able to infer type arguments from whatever you pass in. Copy functiondoSomething<T>(arg: T){// ...}// We can explicitly say that 'T' should be 'string'.doSomething<string>("hello!");// We can also just let the type of 'T' get infe...
letsum =function(input:number[]):number{lettotal:number=0;for(leti =0; i < input.length; i++) {if(isNaN(input[i])) {continue; } total +=Number(input[i]); }returntotal; }console.log(sum([1,2,3])); As before, you'll get type checking and Intellisense when you use a...
functionaddMethod(obj,name,fn){varold=obj[name];obj[name]=function(){if(fn.length===arguments.length){returnfn.apply(this,arguments)}elseif(typeofold==='function'){returnold.apply(this,arguments)}}}varperson={name:'zhangsan'}addMethod(person,'getName',function(){console.log(this.name+'...
function getLen(data : String | any[]):Number{ if(typeof data == 'string'){ console.log("执行data- String 类型 的逻辑") } if(data instanceof Array){ console.log("执行data - Arraty 类型 的逻辑") } return data.length } console.log(getLen("123123")) ...