TypeScript是微软开发的一个开源的编程语言,通过在JavaScript的基础上添加静态类型定义构建而成。TypeScript通过TypeScript编译器或Babel转译为JavaScript代码,可运行在任何浏览器,任何操作系统。
官网地址:https://www.typescriptlang.org/zh/
1. 类型推断
2. 类型注解
let numArr = [1, 2, 3]
const result = numArr.find(item => item >2)
result * 5
let v1: string = 'abc'
let v2: number = 10
let v3: boolean = true
let nu: null = null
let un: undefined = undefined
let v4: string|null = null
let v5: 1 | 2 | 3 = 5
let arr: number[] = [1, 2, 3, 'abc']
let arr1:Array<string> = ['a','b',3]
let t1: [number, string,number] = [1,'a']
let t2: [number, string,number?] = [1,'a']
enum MyEnum{
A,
B,
C
}
console.log(MyEnum.A)
console.log(MyEnum[0])
function aabb(a=10,b: string, c?:boolean, ...rest: number[] ): number{
return 100
}
const f = aabb(1,"2",true, 2,3,4,"a" )
interface Obj{
name: string,
age: number
}
const myobj: Obj = {
name: "a",
age:"10"
sex:5
}
type MyUserName = string | number
let a: string | number = 'abc'
let b: MyUserName = 'abc'
function myFn(a: T, b:T): T[]{
return [a,b]
}
myFn<number>(1,2);//可以
myFn<number>(1, "a");//不可以,报错