TypeScript 语法

变量赋值

• var 不用使用
• let 变量
• const 常量

常用类型赋值

let foo = 'bar';

foo = 'baz';

foo = []
const count = 0;

let isDone: boolean = true;

let num: number = 10;

字符串引用数据

let user = {
    name: 'jack',
    age:18
}

let str: string = `
hello,我叫${user.name}
今年${user.age}
`;

数组元祖赋值

let arr: Array<number> = [1, 2, 3]

let arr: string[] = ['hello', 'hehe']

//元祖结构
let arr:[number,string] = [11,'hehe']

let user:object = {
     name: 'Jack',
     age:18
 }

接口与对象赋值

接口定义

interface Person {
    name: string,
    age: number
}

let user: {
    name: string,
    age: number
} = {
    name: 'Jack',
    age: 11
}

let zs: Person = {
    name: 'zs', 
    age: 12
 }

any的使用

// 在不确定类型的情况下可以使用 anyany
let num: any = 10

num = '20'

let ret: string = (num as string).substr(1)

函数类型声明

类型除了用于变量声明之后,还可以用于函数的形象

 function add(x:number, y:number):number { 
     return x+y
}
var ret = add(10, 20)

函数空返回值

 function fn(): void{ 
     console.log('hello')
 }

数组的解构

let arr: number[] = [10, 20]
let num1: number = arr[0]
// 按照顺序解构赋值
let [num1,num2] = arr

对象的解构

let user = {
    name: 'Jack',
    age: 18
}
//对象按照属性名称解构
//在浏览器环境中,window对象本身有个name
// name的重命名
let { name: nickname, age } = user

function add([x,y]) {
    return x + y
}
add([1,2])

剩余参数 (不定参数)

function sum(...args: number[]):number{
    let ret = 0
    args.forEach(function (item){
        ret += item
    })
    return ret 
}

sum(1, 2, 3)

展开操作符

let arr1 = [1, 2, 3]
let arr2 = [4, 5, 6, ...arr1]


let arr = [...arr1, ...arr2]

let obj1 = {
    foo:'bar'
}
let obj2 = {
    ...obj1,
    name:'Jack'
}