- 只是JavaScript的超集。
- 任何一种JavaScript环境都支持TypeScript。
- 功能更加强大。
- 生态更加健全，完善。
> yarn init --yes
> yarn add typescript --devconst hello = (value: string) => {
console.log(`hello , ${value}`)
}
hello("typeScript") // hello , typeScript> yarn tsc --init会产生一个 「tsconfig.json」文件
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */
/* Basic Options */
// "incremental": true, /* Enable incremental compilation */
"target": "es5", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', 'ES2021', or 'ESNEXT'. */
"module": "commonjs", /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
// "lib": [], /* Specify library files to be included in the compilation. */
// "allowJs": true, /* Allow javascript files to be compiled. */
// "checkJs": true, /* Report errors in .js files. */
// "jsx": "preserve", /* Specify JSX code generation: 'preserve', 'react-native', 'react', 'react-jsx' or 'react-jsxdev'. */
// "declaration": true, /* Generates corresponding '.d.ts' file. */
// "declarationMap": true, /* Generates a sourcemap for each corresponding '.d.ts' file. */
// "sourceMap": true, /* Generates corresponding '.map' file. */
// "outFile": "./", /* Concatenate and emit output to single file. */
// "outDir": "./", /* Redirect output structure to the directory. */
// "rootDir": "./", /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
// "composite": true, /* Enable project compilation */
// "tsBuildInfoFile": "./", /* Specify file to store incremental compilation information */
// "removeComments": true, /* Do not emit comments to output. */
// "noEmit": true, /* Do not emit outputs. */
// "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'. */
// "isolatedModules": true, /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
/* Strict Type-Checking Options */
"strict": true, /* Enable all strict type-checking options. */
// "noImplicitAny": true, /* Raise error on expressions and declarations with an implied 'any' type. */
// "strictNullChecks": true, /* Enable strict null checks. */
// "strictFunctionTypes": true, /* Enable strict checking of function types. */
// "strictBindCallApply": true, /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
// "strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
// "noImplicitThis": true, /* Raise error on 'this' expressions with an implied 'any' type. */
// "alwaysStrict": true, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
// "noUnusedLocals": true, /* Report errors on unused locals. */
// "noUnusedParameters": true, /* Report errors on unused parameters. */
// "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
// "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
// "noUncheckedIndexedAccess": true, /* Include 'undefined' in index signature results */
// "noImplicitOverride": true, /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
// "noPropertyAccessFromIndexSignature": true, /* Require undeclared properties from index signatures to use element accesses. */
/* Module Resolution Options */
// "moduleResolution": "node", /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
// "baseUrl": "./", /* Base directory to resolve non-absolute module names. */
// "paths": {}, /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
// "rootDirs": [], /* List of root folders whose combined content represents the structure of the project at runtime. */
// "typeRoots": [], /* List of folders to include type definitions from. */
// "types": [], /* Type declaration files to be included in compilation. */
// "allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"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. */
// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
/* Source Map Options */
// "sourceRoot": "", /* Specify the location where debugger should locate TypeScript files instead of source locations. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Emit a single file with source maps instead of having a separate file. */
// "inlineSources": true, /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
/* Experimental Options */
// "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
// "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
/* Advanced Options */
"skipLibCheck": true, /* Skip type checking of declaration files. */
"forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */
}
}/**
* 原始类型
* 在typeScript中可以为null
*/
const a:string = "INet"
const b:number = 100
const c:boolean = false
const d:boolean = null
/**
* 新增类型
*/
const e:void = undefined
const f:null = null
const g:undefined = undefined
const h:symbol = Symbol()这样就不会产生变量名冲突的问题。
(function () {
const a = 123
})
const a = 123
export{}表示的是全部类型。
export {}
const a:object = function(){}
const b:{one:number,two:string} = {one:123,two:"123"}export{}
const a:Array<string> = ['1','2','3']
const b:string[] = ['1','2','3']export{}
//元祖类型
//创建一个元祖对象
const a:[number,string] = [1,'2']
//获取元祖对象
const b = a[0]
const c = a[1]export{}
//枚举类型,枚举会污染编译之后代码。变成一个双向的键值对对象。
/**
* 使用对象模拟枚举
*/
const text_status1 = {
drafr:0,
Unpublished: 1,
Published: 2
}
/**
* 在typeScript中可以使用枚举对象
* 数字枚举
*/
enum text_status2 {
drafr = 0,
Unpublished = 1,
Published = 2
}
/**
* 字符串枚举
*/
enum text_status3 {
drafr = 'drafr',
Unpublished = 'Unpublished',
Published = 'Published'
}
/**
* 使用枚举
*/
const text = {
title: 'hello INet',
content: 'This is xiaoXunYao typescript learning notes',
// status: text_status1.drafr
// status: text_status2.drafr
status:text_status3.drafr
}export{}
// 函数声明例子
/**
* 第一个函数类型
* @param a 参数1
* @param b 参数2
* @returns 返回值为string类型
*/
function func1 (a : number,b : number) : string{
return "func1"
}
// 函数表达式的例子
const func2 = function (a : number,b : number) : string{
return 'func2'
}export{}
/**
* any 在TypeScript中不会检查，尽量少用
*/
function stringify(value:any){
return JSON.stringify(value)
}
let a:any = 'string'
let b:any = falseexport{}
//1. 首先我们定一个一个参数，但是不直接赋予对应的类型
//这时候已经将a变量设置为number
let a = 18 // let a: number
//2. 再将a的值变为其他类型
//会产生类型错误的问题
a = "string" //Type 'string' is not assignable to type 'number'.export{}
//1. 假定这个nums有一个明确的接口
const nums = [1,2,3,4]
//2. 找到数组中第一个大于0的数字
const res = nums.find(i => i > 0)
//3. 断言res一定为number类型
const num1 = res as numberexport{}
//接口最主要是拥有那些成员，并且成员类型是如何的
//定义接口
interface post{
title:string
body:string
}
//使用接口
const hello:post = {
title:'this is title',
body:'this is body'
}
//这时候我们就需要让post对象中拥有title和body属性
function printPost(post:post){
console.log(post.title)
console.log(post.body)
}
//可选成员的特性
interface post1{
title:string
body:string
end?:string //添加?即可,这便是可选成员
}
//可以有end这个成员
const demo1:post1 = {
title:'1',
body:'2',
end:'3'
}
//自然也可以没有end这个成员
const demo2:post1 = {
title:'1',
body:'2',
}
//接口的只读属性
interface post2{
title:string
body:string
readonly end:string //在成员的名字前面不在使用readonly关键字就完成了只读属性，一旦赋值就不可修改
}
//动态成员接口
interface post3{
//key是名字，string是类型
[key:string]:string
}用于描述一类具体事物的抽象特征。
export{}
// 类的基础使用
//定义一个类
class Persion{
name : string
age : number
constructor(name : string,age : number){
this.name = name
this.age = age
}
sayHello():void{
console.log(`hello , ${this.name}`)
}
}
// 类的成员访问修饰符
//定义一个类
class dog{
public name : string //将name属性变成共有属性
private age : number //将age变成私有属性,只能在内部访问
protected init : string //将init变成保护属性，只能在内部访问
constructor(name : string,age : number,init : string){
this.name = name
this.age = age
this.init = init
}
sayHello():void{
console.log(`hello , ${this.name}`)
}
}
// 类的继承
class cat extends dog {
constructor(name:string , age:number){
super(name,age,"1");
}
}
//类的只读属性
class persion2{
// 加上 readonly 即可
private readonly name : string
private readonly age : number
constructor(name : string,age : number){
this.name = name
this.age = age
}
sayHello():void{
console.log(`hello , ${this.name}`)
}
}export{}
abstract class Department {
constructor(public name: string) {
}
printName(): void {
console.log('Department name: ' + this.name);
}
abstract printMeeting(): void; // 必须在派生类中实现
}
class AccountingDepartment extends Department {
constructor() {
super('Accounting and Auditing'); // 在派生类的构造函数中必须调用 super()
}
printMeeting(): void {
console.log('The Accounting Department meets each Monday at 10am.');
}
generateReports(): void {
console.log('Generating accounting reports...');
}
}export{}
//不使用泛型
function identity1(arg: number): number {
return arg;
}
//使用泛型
function identity2<T>(arg: T): T {
return arg;
}该项目并不是让大家通过该项目直接掌握TypeScript，该项目仅仅只是作为不敢接触TypeScript的同学的一份小蛋糕。如果想完全掌握TypeScript，可以去官网进行文档学习，我相信如果完成了该项目的所有代码，各位同学对于阅读TypeScript的文档肯定是易如反掌。