1. typescript是什么 #

typescript

2. TypeScript安装和编译 #

2.1 安装 # 

cnpm i typescript -g

tsc helloworld.ts

2.2 Vscode+TypeScript #

2.2.1 生成配置文件 # 

tsc --init

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. 指定ECMAScript的目标版本*/
    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. 指定模块代码的生成方式*/
    // "lib": [],                             /* Specify library files to be included in the compilation. 指定编译的时候用来包含的编译文件*/
    // "allowJs": true,                       /* Allow javascript files to be compiled. 允许编译JS文件*/
    // "checkJs": true,                       /* Report errors in .js files. 在JS中包括错误*/
    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. 指定JSX代码的生成方式 是保留还是react-native或者react*/
    // "declaration": true,                   /* Generates corresponding '.d.ts' file.生成相应的类型声明文件 */
    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. 为每个类型声明文件生成相应的sourcemap*/
    // "sourceMap": true,                     /* Generates corresponding '.map' file. 生成对应的map文件 */
    // "outFile": "./",                       /* Concatenate and emit output to single file. 合并并且把编译后的内容输出 到一个文件里*/
    // "outDir": "./",                        /* Redirect output structure to the directory.按原始结构输出到目标目录 */
    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. 指定输入文件的根目录，用--outDir来控制输出的目录结构*/
    // "composite": true,                     /* Enable project compilation 启用项目编译*/
    // "removeComments": true,                /* Do not emit comments to output. 移除注释*/
    // "noEmit": true,                        /* Do not emit outputs. 不要输出*/
    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. 当目标是ES5或ES3的时候提供对for-of、扩展运算符和解构赋值中对于迭代器的完整支持*/
    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule').r把每一个文件转译成一个单独的模块 */

    /* Strict Type-Checking Options */
    //"strict": true,                           /* Enable all strict type-checking options. 启用完全的严格类型检查 */
    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. 不能使用隐式的any类型*/
    // "strictNullChecks": true,              /* Enable strict null checks. 启用严格的NULL检查*/
    // "strictFunctionTypes": true,           /* Enable strict checking of function types. 启用严格的函数类型检查*/
    // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions.启用函数上严格的bind call 和apply方法 */
    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. 启用类上初始化属性检查*/
    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type.在默认的any中调用 this表达式报错 */
    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. 在严格模式下解析并且向每个源文件中发射use strict*/

    /* Additional Checks */
    // "noUnusedLocals": true,                /* Report errors on unused locals. 有未使用到的本地变量时报错 */
    // "noUnusedParameters": true,            /* Report errors on unused parameters. 有未使用到的参数时报错*/
    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. 当不是所有的代码路径都有返回值的时候报错*/
    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. 在switch表达式中没有替代的case会报错 */

    /* Module Resolution Options */
    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). 指定模块的解析策略 node classic*/
    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. 在解析非绝对路径模块名的时候的基准路径*/
    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. 一些路径的集合*/
    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. 根目录的列表，在运行时用来合并内容*/
    // "typeRoots": [],                       /* List of folders to include type definitions from. 用来包含类型声明的文件夹列表*/
    // "types": [],                           /* Type declaration files to be included in compilation.在编译的时候被包含的类型声明 */
    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking.当没有默认导出的时候允许默认导入，这个在代码执行的时候没有作用，只是在类型检查的时候生效 */
    //"esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'.*/
    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks.不要symlinks解析的真正路径 */

    /* Source Map Options */
    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. 指定ts文件位置*/
    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. 指定 map文件存放的位置 */
    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. 源文件和sourcemap 文件在同一文件中，而不是把map文件放在一个单独的文件里*/
    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. 源文件和sourcemap 文件在同一文件中*/

    /* Experimental Options */
    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. 启动装饰器*/
    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
  }
}

2.2.2 执行编译 # 

tsc

2.2.3 vscode运行 #

2.2.4 npm scripts #

2.2.5 npm scripts 的 PATH #

3. 数据类型 #

3.1 布尔类型(boolean) # 

let married: boolean=false;

3.2 数字类型(number) # 

let age: number=10;

3.3 字符串类型(string) # 

let firstname: string='zfpx';

3.4 数组类型(array) # 

let arr2: number[]=[4,5,6];
let arr3: Array<number>=[7,8,9];

3.5 元组类型(tuple) # 

let zhufeng:[string,number] = ['zhufeng',5];
zhufeng[0].length;
zhufeng[1].toFixed(2);
元组 数组
每一项可以是不同的类型 每一项都是同一种类型
有预定义的长度 没有长度限制
用于表示一个固定的结构 用于表示一个列表 
const animal:[string,number,boolean] = ['zhufeng',10,true];

3.6 枚举类型(enum) #

3.6.1 普通枚举 # 

enum Gender{
    GIRL,
    BOY
}
console.log(`李雷是${Gender.BOY}`);
console.log(`韩梅梅是${Gender.GIRL}`);

enum Week{
    MONDAY=1,
    TUESDAY=2
}
console.log(`今天是星期${Week.MONDAY}`);

3.6.2 常数枚举 # 

const enum Colors {
    Red,
    Yellow,
    Blue
}

let myColors = [Colors.Red, Colors.Yellow, Colors.Blue];

const enum Color {Red, Yellow, Blue = "blue".length};

3.7 任意类型(any) # 

let root:any=document.getElementById('root');
root.style.color='red';

let root:(HTMLElement|null)=document.getElementById('root');
root!.style.color='red';//非空断言操作符

3.8 null 和 undefined # 

let x: number;
x = 1;
x = undefined;    
x = null;   

let y: number | null | undefined;
y = 1;
y = undefined;   
y = null;

3.9 void 类型 # 

function greeting(name:string):void {
    console.log('hello',name);
    //当我们声明一个变量类型是 void 的时候，它的非严格模式(strictNullChecks:false)下仅可以被赋值为 null 和 undefined
    //严格模式(strictNullChecks:true)下只能返回undefined
    //return null;
    //return undefined;
}

3.10 never类型 #

never是其它类型(null undefined)的子类型，代表不会出现的值

3.10.1 # 

// 返回never的函数 必须存在 无法达到（ unreachable ） 的终点
function error(message: string): never {
    throw new Error(message);
}
let result1 = error('hello');
// 由类型推论得到返回值为 never
function fail() {
    return error("Something failed");
}
let result = fail();

// 返回never的函数 必须存在 无法达到（ unreachable ） 的终点
function infiniteLoop(): never {
    while (true) {}
}

3.10.2 strictNullChecks # 

// Compiled with --strictNullChecks
function fn(x: number | string) {
  if (typeof x === 'number') {
    // x: number 类型
  } else if (typeof x === 'string') {
    // x: string 类型
  } else {
    // x: never 类型
    // --strictNullChecks 模式下，这里的代码将不会被执行，x 无法被观察
  }
}

3.10.3 never 和 void 的区别 #

3.11 Symbol # 

const sym1 = Symbol('key');
const sym2 = Symbol('key');
Symbol('key') === Symbol('key') // false

3.12 BigInt # 

const max = Number.MAX_SAFE_INTEGER;// 2**53-1
console.log(max + 1 === max + 2);

const max = BigInt(Number.MAX_SAFE_INTEGER);
console.log(max + 1n === max + 2n);

let foo: number;
let bar: bigint;
foo =bar;
bar = foo;

3.13 类型推论 # 

let username2;
username2 = 10;
username2 = 'zhufeng';
username2 = null;

3.14 包装对象（Wrapper Object） # 

let name = 'zhufeng';
console.log(name.toUpperCase());

console.log((new String('zhufeng')).toUpperCase());

let isOK: boolean = true; // 编译通过
let isOK: boolean = Boolean(1) // 编译通过
let isOK: boolean = new Boolean(1); // 编译失败   期望的 isOK 是一个原始数据类型

3.15 联合类型 # 

let name: string | number;
console.log(name.toString());
name = 3;
console.log(name.toFixed(2));
name = 'zhufeng';
console.log(name.length);

export {};

3.16 类型断言 # 

let name: string | number;
console.log((name as string).length);
console.log((name as number).toFixed(2));
console.log((name as boolean));

双重断言

interface Person {
    name: string;
    age: number;
}
const person = 'zhufeng' as any as Person; // ok

3.17 字面量类型和类型字面量 # 

const up:'Up'= 'Up';
const down: "Down" = "Down";
const left: "Left" = "Left";
const right: "Right" = "Right";
type Direction = 'Up' | 'Down' | 'Left' | 'Right';
function move(direction: Direction) {}
move("Up");

type Person = {
  name:string,
  age:number
};

3.18 字符串字面量 vs 联合类型 #

4. 函数 #

4.1 函数的定义 # 

function hello(name:string):void {
    console.log('hello',name);
}
hello('zfpx');

4.2 函数表达式 # 

type GetUsernameFunction = (x:string,y:string)=>string;
let getUsername:GetUsernameFunction = function(firstName,lastName){
  return firstName + lastName;
}

4.3 没有返回值 # 

let hello2 = function (name:string):void {
    console.log('hello2',name);
    return undefined;
}
hello2('zhufeng');

4.4 可选参数 #

在TS中函数的形参和实参必须一样，不一样就要配置可选参数,而且必须是最后一个参数

function print(name:string,age?:number):void {
    console.log(name,age);
}
print('zfpx');

4.5 默认参数 # 

function ajax(url:string,method:string='GET') {
    console.log(url,method);
}
ajax('/users');

4.6 剩余参数 # 

function sum(...numbers:number[]) {
    return numbers.reduce((val,item)=>val+=item,0);
}
console.log(sum(1,2,3));

4.7 函数重载 # 

let obj: any={};
function attr(val: string): void;
function attr(val: number): void;
function attr(val:any):void {
    if (typeof val === 'string') {
        obj.name=val;
    } else {
        obj.age=val;
    }
}
attr('zfpx');
attr(9);
attr(true);
console.log(obj);

5. 类 #

5.1 如何定义类 # 

class Person{
    name:string;
    getName():void{
        console.log(this.name);
    }
}
let p1 = new Person();
p1.name = 'zhufeng';
p1.getName();

/**
 * 当我们写一个类的时候,会得到2个类型
 * 1. 构造函数类型的函数类型
 * 2. 类的实例类型
 */
class Component {
    static myName: string = '静态名称属性';
    myName: string = '实例名称属性';
}
let com = Component;
//Component类名本身表示的是实例的类型
//ts 一个类型 一个叫值 
//冒号后面的是类型
//放在=后面的是值
let c: Component = new Component();
let f: typeof Component = com;

5.2 存取器 # 

class User {
    myname:string;
    constructor(myname: string) {
        this.myname = myname;
    }
    get name() {
        return this.myname;
    }
    set name(value) {
        this.myname = value;
    }
}

let user = new User('zhufeng');
user.name = 'jiagou'; 
console.log(user.name); 

"use strict";
var User = /** @class */ (function () {
    function User(myname) {
        this.myname = myname;
    }
    Object.defineProperty(User.prototype, "name", {
        get: function () {
            return this.myname;
        },
        set: function (value) {
            this.myname = value;
        },
        enumerable: true,
        configurable: true
    });
    return User;
}());
var user = new User('zhufeng');
user.name = 'jiagou';
console.log(user.name);

5.3 参数属性 # 

class User {
    constructor(public myname: string) {}
    get name() {
        return this.myname;
    }
    set name(value) {
        this.myname = value;
    }
}

let user = new User('zhufeng');
console.log(user.name); 
user.name = 'jiagou'; 
console.log(user.name);

5.4 readonly # 

class Animal {
    public readonly name: string
    constructor(name:string) {
        this.name = name;
    }
    changeName(name:string){
        this.name = name;
    }
}

let a = new Animal('zhufeng');
a.changeName('jiagou');

5.5 继承 # 

class Person {
    name: string;//定义实例的属性，默认省略public修饰符
    age: number;
    constructor(name:string,age:number) {//构造函数
        this.name=name;
        this.age=age;
    }
    getName():string {
        return this.name;
    }
    setName(name:string): void{
        this.name=name;
    }
}
class Student extends Person{
    no: number;
    constructor(name:string,age:number,no:number) {
        super(name,age);
        this.no=no;
    }
    getNo():number {
        return this.no;
    }
}
let s1=new Student('zfpx',10,1);
console.log(s1);

5.6 类里面的修饰符 # 

class Father {
    public name: string;  //类里面 子类 其它任何地方外边都可以访问
    protected age: number; //类里面 子类 都可以访问,其它任何地方不能访问
    private money: number; //类里面可以访问， 子类和其它任何地方都不可以访问
    constructor(name:string,age:number,money:number) {//构造函数
        this.name=name;
        this.age=age;
        this.money=money;
    }
    getName():string {
        return this.name;
    }
    setName(name:string): void{
        this.name=name;
    }
}
class Child extends Father{
    constructor(name:string,age:number,money:number) {
        super(name,age,money);
    }
    desc() {
        console.log(`${this.name} ${this.age} ${this.money}`);
    }
}

let child = new Child('zfpx',10,1000);
console.log(child.name);
console.log(child.age);
console.log(child.money);

5.7 静态属性 静态方法 # 

class Father {
    static className='Father';
    static getClassName() {
        return Father.className;
    }
    public name: string;
    constructor(name:string) {//构造函数
        this.name=name;
    }

}
console.log(Father.className);
console.log(Father.getClassName());

5.8 抽象类 # 

abstract class Animal {
    name!:string;
    abstract speak():void;
}
class Cat extends Animal{
    speak(){
        console.log('喵喵喵');
    }
}
let animal = new Animal();//Cannot create an instance of an abstract class
animal.speak();
let cat = new Cat();
cat.speak();
访问控制修饰符 private protected public
只读属性 readonly
静态属性 static
抽象类、抽象方法 abstract

5.9 抽象方法 # 

abstract class Animal{
    abstract speak():void;
}
class Dog extends  Animal{
    speak(){
        console.log('小狗汪汪汪');
    }
}
class Cat extends  Animal{
    speak(){
        console.log('小猫喵喵喵');
    }
}
let dog=new Dog();
let cat=new Cat();
dog.speak();
cat.speak();

5.10 重写(override) vs 重载(overload) # 

class Animal{
    speak(word:string):string{
        return '动作叫:'+word;
    }
}
class Cat extends Animal{
    speak(word:string):string{
        return '猫叫:'+word;
    }
}
let cat = new Cat();
console.log(cat.speak('hello'));
//--------------------------------------------
function double(val:number):number
function double(val:string):string
function double(val:any):any{
  if(typeof val == 'number'){
    return val *2;
  }
  return val + val;
}

let r = double(1);
console.log(r);

5.11 继承 vs 多态 # 

class Animal{
    speak(word:string):string{
        return 'Animal: '+word;
    }
}
class Cat extends Animal{
    speak(word:string):string{
        return 'Cat:'+word;
    }
}
class Dog extends Animal{
    speak(word:string):string{
        return 'Dog:'+word;
    }
}
let cat = new Cat();
console.log(cat.speak('hello'));
let dog = new Dog();
console.log(dog.speak('hello'));

6. 接口 #

6.1 接口 #

6.1.1 对象的形状 # 

//接口可以用来描述`对象的形状`,少属性或者多属性都会报错
interface Speakable{
    speak():void;
    name?:string;//？表示可选属性
}

let speakman:Speakable = {
    speak(){},//少属性会报错
    name,
    age//多属性也会报错
}

6.1.2 行为的抽象 # 

//接口可以在面向对象编程中表示为行为的抽象
interface Speakable{
    speak():void;
}
interface Eatable{
    eat():void
}
//一个类可以实现多个接口
class Person implements Speakable,Eatable{
    speak(){
        console.log('Person说话');
    }
    eat(){}
}
class TangDuck implements Speakable{
    speak(){
        console.log('TangDuck说话');
    }
    eat(){}
}

6.1.3 任意属性 # 

//无法预先知道有哪些新的属性的时候,可以使用 `[propName:string]:any`,propName名字是任意的
interface Person {
  readonly id: number;
  name: string;
  [propName: string]: any;
}

let p1 = {
  id:1,
  name:'zhufeng',
  age:10
}

6.2 接口的继承 # 

interface Speakable {
    speak(): void
}
interface SpeakChinese extends Speakable {
    speakChinese(): void
}
class Person implements SpeakChinese {
    speak() {
        console.log('Person')
    }
    speakChinese() {
        console.log('speakChinese')
    }
}

6.3 readonly # 

interface Person{
  readonly id:number;
  name:string
}
let tom:Person = {
  id :1,
  name:'zhufeng'
}
tom.id = 1;

6.4 函数类型接口 # 

interface discount{
  (price:number):number
}
let cost:discount = function(price:number):number{
   return price * .8;
}

6.5 可索引接口 # 

interface UserInterface {
  [index:number]:string
}
let arr:UserInterface = ['zfpx1','zfpx2'];
console.log(arr);

interface UserInterface2 {
  [index:string]:string
}
let obj:UserInterface2 = {name:'zhufeng'};

6.6 类接口 # 

interface Speakable {
    name: string;
    speak(words: string): void
}
class Dog implements Speakable {
    name!: string;
    speak(words:string) {
        console.log(words);
    }
}
let dog = new Dog();
dog.speak('汪汪汪');

6.7 构造函数的类型 # 

class Animal{
  constructor(public name:string){
  }
}
//不加new是修饰函数的,加new是修饰类的
interface WithNameClass{
  new(name:string):Animal
}
function createAnimal(clazz:WithNameClass,name:string){
   return new clazz(name);
}
let a = createAnimal(Animal,'zhufeng');
console.log(a.name);

6.8 抽象类 vs 接口 # 

abstract class Animal{
    name:string;
    constructor(name:string){
      this.name = name;
    }
    abstract speak():void;
  }
interface Flying{
      fly():void
}
class Duck extends Animal implements Flying{
      speak(){
          console.log('汪汪汪');
      }
      fly(){
          console.log('我会飞');
      }
}
let duck = new Duck('zhufeng');
duck.speak();
duck.fly();

7. 泛型 #

7.1 泛型函数 # 

function createArray(length: number, value: any): Array<any> {
  let result: any = [];
  for (let i = 0; i < length; i++) {
    result[i] = value;
  }
  return result;
}
let result = createArray(3,'x');
console.log(result);

使用了泛型

function createArray<T>(length: number, value: T): Array<T> {
    let result: T[] = [];
    for (let i = 0; i < length; i++) {
      result[i] = value;
    }
    return result;
  }
let result = createArray2<string>(3,'x');
console.log(result);

7.2 类数组 # 

function sum() {
    let args: IArguments = arguments;
    for (let i = 0; i < args.length; i++) {
        console.log(args[i]);
    }
}
sum(1, 2, 3);

let root = document.getElementById('root');
let children: HTMLCollection = (root as HTMLElement).children;
children.length;
let nodeList: NodeList = (root as HTMLElement).childNodes;
nodeList.length;

7.3 泛型类 #

7.3.1 泛型类 # 

class MyArray<T>{
    private list:T[]=[];
    add(value:T) {
        this.list.push(value);
    }
    getMax():T {
        let result=this.list[0];
        for (let i=0;i<this.list.length;i++){
            if (this.list[i]>result) {
                result=this.list[i];
            }
        }
        return result;
    }
}
let arr=new MyArray();
arr.add(1); arr.add(2); arr.add(3);
let ret = arr.getMax();
console.log(ret);

7.3.2 泛型与 new # 

function factory<T>(type: {new():T}): T {
  return new type(); // This expression is not constructable.
}

7.5 泛型接口 # 

interface Calculate{
  <T>(a:T,b:T):T
}
let add:Calculate = function<T>(a:T,b:T){
  return a;
}
add<number>(1,2);

7.6 多个类型参数 # 

function swap<A,B>(tuple:[A,B]):[B,A]{
  return [tuple[1],tuple[0]];
}
let swapped = swap<string,number>(['a',1]);
console.log(swapped);
console.log(swapped[0].toFixed(2));
console.log(swapped[1].length);

7.7 默认泛型类型 # 

function createArray3<T=number>(length: number, value: T): Array<T> {
  let result: T[] = [];
  for (let i = 0; i < length; i++) {
    result[i] = value;
  }
  return result;
}
let result2 = createArray3(3,'x');
console.log(result2);

7.8 泛型约束 # 

function logger<T>(val: T) {
    console.log(val.length); //直接访问会报错
}
//可以让泛型继承一个接口
interface LengthWise {
    length: number
}
//可以让泛型继承一个接口
function logger2<T extends LengthWise>(val: T) {
    console.log(val.length)
}
logger2('zhufeng');
logger2(1);

7.9 泛型接口 # 

interface Cart<T>{
  list:T[]
}
let cart:Cart<{name:string,price:number}> = {
  list:[{name:'zhufeng',price:10}]
}
console.log(cart.list[0].name,cart.list[0].price);

7.10 compose #

compose

import compose from ".";
/* zero functions */
console.log(compose()<string>("zhufeng"));
/* one functions */
interface F{
    (a:string):string
}
let f: F = (a:string):string=>a+'f';
console.log(compose<F>(f)("zhufeng"));
/* two functions */
type A = string;
type R = string;
type T = string[];

let f1 = (a: A): R => a + "f1";
let f2 = (...a: T): A => a + "f2";
console.log(compose<A,T,R>(f1,f2)("zhufeng"));

7.11 泛型类型别名 # 

type Cart<T> = {list:T[]} | T[];
let c1:Cart<string> = {list:['1']};
let c2:Cart<number> = [1];

7.12 泛型接口 vs 泛型类型别名 #

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