typescript定义类型

原创已于 2022-11-30 15:07:36 修改 · 310 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#typescript #javascript #前端

于 2022-11-29 17:01:17 首次发布

TypeScript 专栏收录该内容

3 篇文章

订阅专栏

个人学习笔记，供参考

// 定义数组的几种方式
let a: number[] = [1, 2, 3, NaN, Infinity];
let f: number[][] = [[1], [2], [3], [NaN], [Infinity]];
let b: Array<number> = [1, 2, 3];
let e: Array<Array<number>> = [[1], [2]];
let c: (string | number)[] = [1, "n"];

type Example = (number | string | void)[];
let d: Example = [1, "a", undefined];

// 接口和对象类型
interface A {
  readonly name: string; //只读属性
  age: number;
  phone?: number;
  cb?(): number;
  [propName: string]: any; //使对象可添加任意属性，会限制该接口所有属性的类型
}
interface B extends A {
  run: number;
}
interface C {
  sex: string;
}
let obj: A = {
  name: "hh",
  age: 12,
  phone: 12344,
  eat: "水煮鱼",
  cb: () => {
    return 123;
  },
};
let obj1: A = {
  name: "hhs",
  age: 12,
  sing: true,
};
let obj2: B = {
  name: "hhs",
  age: 12,
  run: 123,
};
// 类型别名
type Person = {
  name: string;
  age: number;
};

// 函数类型
// 定义函数参数、返回值类型
function fun(a: number, b: number = 10): number {
  return a + b;
}
const add: (a: number, b: number) => number = (a, b) => {
  return a + b;
}; // 只适用于函数表达式

// 如果函数没有返回值，则返回类型为void
function greet(name: string): void {
  console.log("该函数没有返回值", name);
}
function fun1(user: A) {
  console.log(user);
}
fun1(obj1); //{name: "hhs",age: 12,sing: true,}

// 交叉类型
function fun2(man: A & C): void {
  console.log(man);
}
fun2({ ...obj1, sex: "男" }); //{name: "hhs",age: 12,sing: true, sex:'男'}

// 断言as
function fun3(num: A | C): void {
  console.log((num as C).sex);
  //   console.log((<C>num).length);
}
fun3({ sex: "nv" }); //nv
fun3(obj1); //undefined

内置对象

html

<div class="test-div">HTMLDivElement</div>
<ul class="list">
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
</ul>

// ECMAscript的内置对象
const reg: RegExp = /\w\d\s/; // /\w\d\s/
const date: Date = new Date(); // 2022-11-29T09:27:28.133Z
const err: Error = new Error("错误");
let bool: Boolean = new Boolean(1); // [Boolean: true]
let n: Number = new Number(true); // [Number: 1]
let str: String = new String("字符串"); // [String: '字符串']

// DOM、BOM的内置对象
const list: NodeList = document.querySelectorAll(".list li");
const body: HTMLElement = document.body;
// console.dir()查看标签类型
const div = document.querySelector(".test-div") as HTMLDivElement;
document.addEventListener("click", (e: MouseEvent) => {
  console.log(e);
});