Typescript
Typescript学习笔记。From zero to hero。 1. Array,Tuple,Union,Enum // Basic Types let id: number = 5 //变量后面加类型，用冒号隔开 let company: string = 'Traversy Media' let isPublished: boolean = true let x: any = 'Hello' //any类型变量，可以放任何类型数据 let ids: number[] = [1, 2, 3, 4, 5] //不定长数组 区别传统静态语言的int a[4]; let arr: any[] = [1, true, 'Hello'] //any数组，可以混合各种值 // Tuple let person: [number, string, boolean] = [1, 'Brad', true] //元组：已知元素数量和类型的数组，各元素的类型不必相同。 // Tuple Array let employees: [number, string][] //每个元素是元组的数组 employee = [ [1, 'Brad'], [2, 'John'], [3, 'Jill'], ] // Union let pid: string | number //联合 /* 以下是C语言的联合，都是一个变量可以存几种不同类型数据 union data{ int n; char ch; double f; }; */ pid = '22' // Enum enum Direction1 { Up = 1, Down, Left, Right, } enum Direction2 { Up = 'Up', Down = 'Down', Left = 'Left', Right = 'Right', } 2. Map //定义 type MapType = { [id: string]: string; } //实例化 const map: MapType = {}; map['a'] = 'b'; map['c'] = 'd'; //删除 delete map['c']; //枚举 for (let i in map) { console.log(map[i]); } //得到包含所有key的数组 console.log(Object.keys(map)); //另外一种用Record的实现方式 const map: Record<string, string> = {}; map['a'] = 'b'; map['c'] = 'd'; 3. Object // Objects type User = { id: number name: string } const user: User = { id: 1, name: 'John', } // Type Assertion 类型的选择 let cid: any = 1 // let customerId = <number>cid 从any到 number 的选择 let customerId = cid as number 4. Function // Functions function addNum(x: number, y: number): number { return x + y } // Void function log(message: string | number): void { console.log(message) } 5. Interface, Class // Interfaces interface UserInterface { readonly id: number name: string age?: number } const user1: UserInterface = { id: 1, name: 'John', } interface MathFunc { (x: number, y: number): number } const add: MathFunc = (x: number, y: number): number => x + y const sub: MathFunc = (x: number, y: number): number => x - y interface PersonInterface { id: number name: string register(): string } // Classes class Person implements PersonInterface { id: number name: string constructor(id: number, name: string) { this.id = id this.name = name } register() { return `${this.name} is now registered` } } const brad = new Person(1, 'Brad Traversy') const mike = new Person(2, 'Mike Jordan') // Subclasses class Employee extends Person { position: string constructor(id: number, name: string, position: string) { super(id, name) this.position = position } } const emp = new Employee(3, 'Shawn', 'Developer') 6. Generics // Generics => C++的泛型 function getArray<T>(items: T[]): T[] { return new Array().concat(items) } let numArray = getArray<number>([1, 2, 3, 4]) let strArray = getArray<string>(['brad', 'John', 'Jill']) strArray.push(1) // Throws error 7. FAQ 7.1. type alias or interface https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#differences-between-type-aliases-and-interfaces ...
