The use of interface, type and Record in typescript

Use of interface, type and Record in vite+vue3+ts

Use of interface, type and Record in vite+vue3+ts

interface: interface

Chinese official document: https://www.tslang.cn/docs/handbook/interfaces.html

type: type alias

https://www.tslang.cn/docs/handbook/advanced-types.html
https://www.typescriptlang.org/docs/handbook/2/keyof-types.html

basic type

type Person = string;

combination

interface People {
  name: string,
  weight: number
}
type Animal = {
  name: string,
}
type Cat = People | Animal

type Fruit = 'apple' | 'pear' | 'orange';
type Vegetable = 'broccoli' | 'carrot' | 'lettuce';

// 'apple' | 'pear' | 'orange' | 'broccoli' | 'carrot' | 'lettuce';
type HealthyFoods = Fruit | Vegetable;

const bf: HealthyFoods = 'broccoli';
console.log(bf);

const useDemo = function (food: HealthyFoods) {
  console.log(`Eating ${food}`);
}
useDemo('carrot');

tuple

Tuples combine values of different types in a predefined order, each position has a fixed type, and the order of the positions is determined when it is defined

type ResponseCode = [string, number];

interface Dog {
  name: string;
}
interface Cat {
  age: number;
}
type Animal = [Dog, Cat];

// 创建一个 Animal 元组实例
const animal1: Animal = [
  { name: "Fido" },
  { age: 3 }
];
console.log(animal1[0].name); // 输出: "Fido"
console.log(animal1[1].age); // 输出: 3

type capture

const orange = { color: "Orange", vitamin: 1}
// { color: string, vitamin: number }
type Fruit = typeof orange
let apple: Fruit;
apple = { color: "Red", vitamin: 2 }

type will automatically capture that color is a string type and vitamin is a number type

let div = document.createElement("div");
type B = typeof div; // HTMLDivElement

traverse properties

type Keys = "firstName" | "lastName";

type Name = {
  [key in Keys]: string;
};

const myName: Name = {
  firstName: "kelen",
  lastName: "huang",
};

expand

interface is always extensible

interface extends interface (merged)

interface Animal {
  name: string
}
interface Animal {
  honey: boolean
}
// 定义bear的实例
const bear: Animal = {
  name: 'wine',
  honey: true
}

interface extends interface (inheritance)

interface Animal {
  name: string
}
interface Bear extends Animal {
  honey: boolean
}

const bear: Bear = {
  name: 'wine',
  honey: true
}
// 如果不写honey属性就会报错

type extends type (merge)

After the type is created, it cannot be changed, and it cannot be extended by the same name, only by &de-extending

type Animal {
  name: string
}
type Bear & Animal {
  honey: boolean
}
// 定义bear的实例
const bear:Bear = {
  name: 'wine',
  honey: true
}

interface extension type

type Animal = {
  name: string,
}

interface Bear extends Animal {
  honey: boolean;
}

type extends interface

interface Animal {
  name: string,
}

type Bear = Animal & {
  honey: boolean
}

Record

https://www.typescriptlang.org/docs/handbook/utility-types.html#recordkeys-type

Record<key type, value type>The first keyvalue type, the second is obj[key]the data type
Record<string, unknown>any object

easy to use

let termMap1 = {} as Record<string, string>;
// 定义对象 Record<string, string> 第一个string为key值，第二个为obj[key]数据的类型
termMap1 = {
  age:10, // 不能将类型“number”分配给类型“string”。
  num:'11'
}
console.log('termMap1',termMap1 );

complex object

// Record 来限制 对象的key和value
type P = {
  [key: string]: number;
};
let p: P = { ppp: 10, ooo: 10 };
// k不是泛型  K泛型

// 01 Record 来限制 对象的key和value
type PP = Record<string, number>;
let pp: PP = {
  ppp: 10,
  ooo: 10,
};

type PP2 = Record<string, string>;
let pp2: PP2 = {
  ppp: "10", //  ppp: '10' 不能将类型“number”分配给类型“string”
  ooo: "10",
};

// 02 Record 来限制 复杂对象的key和value
interface term {
  info: number;
  checked: boolean;
}
type TermMap = Record<string, term>;
// item项目  key:string  value: { info: 10, checked: true }
let termMap: TermMap = {
  xxx: {
    info: 10,
    checked: true,
  },
};

// 03 Record 来限制 复杂对象的key和value
interface info_config {
  name: string;
}
interface term2 {
  info: info_config;
  checked: boolean;
}
let termMap2 = {} as Record<string, term2>;
// 定义对象 Record<string, string> 第一个string为key值，第二个为obj[key]数据的类型
termMap2 = {
  xxx: {
    info: {
      name: "111",
    },
    checked: true,
  },
};

// 04 Record 来限制 复杂对象的key和value
interface info_config3 {
  name: string[];
}
interface term3 {
  info: info_config3;
  checked: boolean;
}
let termMap3 = {} as Record<string, term3>;
// 定义对象 Record<string, string> 第一个string为key值，第二个为obj[key]数据的类型
termMap3 = {
  xxx: {
    info: {
      name: ["1", "2"],
    },
    checked: true,
  },
};