1.typescript代码练习

let message:string ='hello nice day';

console.log(message);  

console.log("ok,good luck11111111111");

let a = 1+2;

let b= a+3;

let c={

    apple:a,

    banana:b

};

let d = c.apple * 4;

console.log(d);

let aa = true

let bb:boolean = false

let ee: true = true  //指定ee类型是true,就只能赋值true

let ff:false= false //指定ff类型是false,就只能赋值false

let a1 = 1234;

var b1 = Infinity *0.10

const c1 =5678

let e1:number = 100

let a_str = "hello"

let a_str2:string = "hello2"

console.log(a_str);

//let a2:bigint = 100

let a_obj:object = {

    b:"x"

} //无法访问b

let a_obj2 = { //对象

    b:"x"

} //可以访问b

console.log(a_obj2.b)

let a_obj3:(b:number)=>

{

    b:11

}

//console.log(a_obj3.b) 无法访问

let c_a:{

    firstName:string

    lastName:string

}={

    firstName:"t",

    lastName:"zhan"

}

c_a.firstName //可以访问

class Person{

    constructor(

        public firstName:string,

        public lastName:string

    ){}

}

c_a = new Person("mt1","zhou")

let i:number=3; //声明变量，必须赋值

let j = i*3;

//索引

let airplaneSeatingAssignments:

{

    [seatNunber:string]:string

} = {

    "2D":"tt",

    "2F":"zz5"

}

let loc2 = airplaneSeatingAssignments["2D"]

console.log("索引："+loc2)

airplaneSeatingAssignments["2D"]="t3x"

loc2 = airplaneSeatingAssignments["2D"]

console.log("索引："+loc2)

let user:{

    readonly firstName:string,

    lastName:string

} ={

    firstName:"lubby",

    lastName:"nice"

}

//user.firstName = "11"

user.lastName = "ss"

type Color = "red"

//type Color ="blue"

let x = Math.random()<.5

if(x)

{

    type Color ="blue" //type类型别名

    let b:Color ='blue'

}

else

{

    let c:Color="red"

}

//DRY是什么意思：Don't Repeat Yourself

//并集，| ，交集：&

type Cat = {name:string,purrs:boolean}

type Dog = {name:string,barks:boolean,wags:boolean}

type CarOrDogOrBoth = Cat|Dog

type CatAndDog = Cat & Dog

let a11:CarOrDogOrBoth = {  //cat

    name:"bonk",

    purrs:true

}

a11 = {  //dog

    name:"domi",

    barks:true,

    wags:true

}

//二者兼具

a11 ={

    name:"donk",

    barks:true,

    purrs:true,

    wags:true

}

//交集

let b11:CatAndDog ={

    name:"domin",

    barks:true,

    purrs:true,

    wags:true

}

function trueOrNull(isTrue:boolean)

{

    if(isTrue)

    {

        return "true"

    }

    return null;

}

type Returns = string | null

function aaa(a:string,b:number)//函数创建，方法

{

    return a||b

}

//数组

let a_group = [1,2,3]

var b_g= ['a','b']

let c_g:string[] =["a"]

let d_group =[1,"a"] //(string|number)[]

let f_group =["red"]

f_group.push("blue")

f_group.push("ccd")

//f_group.push(true)

let g=[] //any[]

g.push(1)

g.push('red') //(string|number)[]

let hh:number[] = []//number[]

hh.push(1)

//hh.push("read")//指定Number就只能赋值Number

let d_47 = [1,"a"]

d_47.map(ff=>{

    if(typeof(ff)=="number")

    {

        return ff*3

    }

    return ff.toUpperCase()

})

function buildArray2()

{

    let a=[]

    a.push(1)

    a.push("x")

    return a

}

let myArr = buildArray2()  

//myArr.push(true)

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