前端开发TypeScript入门基础教程

npm install -g typescript

tsc -V 

const str:string ="hello world TS";
console.log(str)

tsc test1.ts

PS E:\mysjc\ts> node test1.js
hello world TS
PS E:\mysjc\ts> 

const str1: string = "hello world";
const str2: string = 'ts';
const str3: string = `年少不知富婆好，${ str1 } ${ str2 } `;

const num1: number = 3;// 十进制
const num2: number = 3.3;
const num3: number = 3.333;
const num4: number = 0b11;// 二进制
const num5: number = 0o12;// 八进制 
const num6: number = 0xa; // 十六进制 

const bol1: boolean=false;
const bol2: boolean=true;

const list1: number[]=[1,2,3]; // 可以试试 list1[0]='2'，会发生什么。
const list2: Array<number>=[1,2,3];

enum Animal {
    Dog,
    Cat,
    Pig
  }
  let zhangsan: Animal = Animal.Dog 
  console.log(zhangsan, Animal.Cat, Animal.Pig) ;// 0 1 2

  enum Animal {
    Dog="狗",
    Cat="猫",
    Pig="猪"
  }
  let zhangsan: Animal = Animal.Dog 
  console.log(zhangsan, Animal.Cat, Animal.Pig) ;// 狗 猫 猪

let a: any = [1,undefined,null,'string',true,false];
a[0]='s';
console.log(a); //[ 's', undefined, null, 'string', true, false ] 
let b: any=1;
b='wc';
b=null;
console.log(b); //null

// The parameter's type annotation is an object type
function printCoord(pt: { x: number; y: number }) {
    console.log("The coordinate's x value is " + pt.x);
    console.log("The coordinate's y value is " + pt.y);
}
printCoord({ x: 3, y: 7 });

function printName(obj: { first: string; last?: string }) {
    console.log(`${obj.first}-${obj.last}`);
}
printName({ first: "Bob" }); //Bob-undefined
printName({ first: "Alice", last: "Alisson" }); //Alice-Alisson

function printName(obj: { first: string; last?: string }) {
    // obj.last.toUpperCase(); // TypeError: Cannot read property 'toUpperCase' of undefined
    if (obj.last !== undefined) {
        console.log("if", obj.last.toUpperCase());
    }
    console.log(obj.last?.toUpperCase());
}
printName({ first: "Bob" }); // undefined

printName({ first: "Bob", last: "aa" });

function work(id: number | string) {
    console.log("上班:" + id);
}
work(101);//上班:101
work("202");//  上班:202
//  work(false); 

function work(id: number | string) {
    const salary: number = 300;
    if (typeof id === "string") {
        console.log(`${id}上班,可获得薪水$${salary}`);
    } else {
        console.log(`${id}上班,可获得薪水$${salary * 2}`);
    }
}
work(101); //101上班,可获得薪水$600
work("202"); //202上班,可获得薪水$300

console.log(1 as string)
console.log(<string>1 )

let a = 1;
a = '11';//不能将类型“string”分配给类型“number”
let b;
b = 1;
b = '1';
b = null;