2 数据类型

1-基本数据类型声明

var s:string="hello"
var n:number = 10
var b:boolean = true

2-可先声明变量再赋值

var num:number;
num = 19;

3-可以声明多个类型

var good:number | undefined;

4-复杂数据类型

 1、array 数组
var arr:string [] = ['html','css','js'];
var newArr:Array<number> = [1,2,3]  //推荐这种
//console.log(typeof arr)  // object
2、object
var obj:Object={name:"dai",age:18}
3、array-object
var list:Array<object>=[{name:"dai"}]

5-元组

// 元组 在ts 中计算一个被限定了item值类型的数组
let Arr:[number,string] = [12,"hello"]

6-函数

// 声明一个有返回值的函数
function go():string{
    return "hello world"
}
// 声明没有返回值的函数
function show():void{
    console.log("hello world")
}
console.log(go())  //hello world
show()
local('top')  //top

// 函数传参
function fun(s:string):string{
    console.log(s)
    return s
}
fun('hello')
//默认参数
function fun2(s:string="hello"):string{
    console.log(s)
    return s
}
fun2('good')
// 任意类型 any
function fun3(s:any):any{
    console.log(s)
    return s
}
//支持箭头函数
var goTo=()=>{
    console.log("go");
}
goTo() //go

7-class

class Student{
    name:string;
    age:number;
    constructor(name:string,age:number){
        this.name = name;
        this.age = age
    }
    getName():void{
        console.log(this.name);   
    }
}
var s:Student = new Student("dai",18);
s.getName();//dai

class Person{
    name:string;
    age:number;
    constructor(name:string,age:number){
        this.name = name;
        this.age = age
    }
    getName():void{
        console.log(this.name);   
    }
}
class Student extends Person{
    skill:string;
    constructor(name:string,age:number,skill:string){
        super(name,age)
        this.skill = skill;
    }
    getSkill():void{
        console.log(this.skill);
    }
}
var s:Student = new Student("dai",18,"web前端");
var p:Person = new Person('lisi',19);
s.getName();//dai
// p.getSkill();  //报错  父类不能调用子类的方法

8-枚举类型 enum

enum Skills{html,css,js}
var j:Skills = Skills.html;
console.log(j) // 输出下标值
enum Status {
    success=200,
    error=404,
    serverError=500
}
var success:Status = Status.success
console.log(success)

9-null - undefined

var num = null;
num =10 //报错
let x: number | null | undefined;
x = 1; // 运行正确
x = undefined;    // 运行正确
x = null;    // 运行正确

10-Dart语法(Google)