编辑代码

// let age:number = 50
// let height:number = 175.5
// let isStudent:boolean = true
// let isOpen:boolean = false
// let name: string = "Alice"
// let greeting: string = 'Hello, TypeScript!';
// let score:number|null = null
// let description:string|undefined = undefined
// const symbol1 =  Symbol("key1")
// const symbol2 =  Symbol("key2")
// let value:any = 2
// value = "111"
// value = true
// function test(message: string): void {

// }

// function throwError(message: string): never {
//     throw Error(message)
// }

// let person = {
//     name : "John",
//     age : 30,
//     greet() {
//         console.log("Hello, I'm" this.name);
//     }
// }


let a: number[] = [1, 2, 3];
let b: Array<number> = [2, 3, 5];

let c: [number, string] = [5, "11"];

enum Color {
    Red = 2,
    Green,
    Blue
}
let color: Color = Color.Red;
console.log(color)

let aunknown: unknown = 5;

function aa(): void {
    console.info("aa")
}
aa()

let undefinedvar: undefined = undefined;
let nullvar: null = null;

let unionvar: number | string = 5;

console.log("aunknown===unionvar:" + (aunknown === unionvar));

function test2(num: number, num2?: number) {
    if (num2) {
        console.log("num2:" + num2);
    } else {
        console.log("num:" + num);
    }
}
test2(1, 2);
test2(5);

function test3(...arr: number[]) {
    for (let num of arr) {
        console.log(num)
    }
}

test3(1, 55, 6);
test3(25);