TypeScript思维导图 - TS攻坚|关键词 - 《前端手册》

type A = {
    name: String;
}
type B = {
    age: number;
}
type Person = A & B;
let jack: Person = {
    name: 'jack',
    age: 20,
}

截屏2021-12-02 上午11.42.37.png

type A = string | number;
let a: A = 'hello';
let b: A = 12;

截屏2021-12-02 上午11.43.31.png

let obj = {}
obj.a;
obj?.b;
obj?.['c'];

只检验左侧是否为undefined或null
注意0、false会产生短路

console.log(undefined ?? 2); 
console.log(null ?? 3);
console.log(0 ?? 3);
console.log(false ?? 3);

type A = string | undefined | null;
function showType(args: A) {
    let str1: string = args;
    let str2: string = args!;
}

截屏2021-12-02 上午11.49.16.png

instaceofΩ

keyof

O[K]

[K in O]

+、-、readonly

X ? Y : Z

TS攻坚|关键词