Typescript类型定义
代码示例
typescript中的自定义类型
// simple type
type Websites = 'www.google.com' | 'reddit.com';
let mySite: Websites = 'www.google.com' //pass
//or
let mySite: Website = 'www.yahoo.com' //error
// the above line will show error because Website type will only accept 2 strings either 'www.google.com' or 'reddit.com'.
// another example.
type Details = { id: number, name: string, age: number };
let student: Details = { id: 803, name: 'Max', age: 13 }; // pass
//or
let student: Details = { id: 803, name: 'Max', age: 13, address: 'Delhi' } // error
// the above line will show error because 'address' property is not assignable for Details type variables.
//or
let student: Details = { id: 803, name: 'Max', age: '13' }; // error
// the above line will show error because string value can't be assign to the age value, only numbers.
typescript函数类型
// define your parameter's type inside the parenthesis
// define your return type after the parenthesis
function sayHello(name: string): string {
console.log(`Hello, ${name}`!);
}
sayHello('Bob'); // Hello, Bob!typescript类型定义
// cannot use object for type defination because this is not recommended
// use Record<string, any> this same with object
const name: string = "john doe"
const age: number = 30
const days1: string[] = ["sunday","monday","thuesday","wenesday"]
const numb1: number[] = [1,2,3,4,5]
const days2: Array<string> = ["sunday","monday","thuesday","wenesday"]
const numb2: Array<number> = [1,2,3,4,5]
const person: Record<string, any> = {
name: "john doe",
age: 30
}
async function name(): Promise<string> {
return "john doe"
}
name().then(console.log)
async function str(): Promise<string[]> {
return ["sunday","monday","thuesday","wenesday"]
}
str().then(console.log)
async function int(): Promise<int[]> {
return [1,2,3,4,5]
}
int().then(console.log)
async function objectValue(): Promise<Record<string, any>> {
const person: Record<string, any> = {
name: "john doe",
age: 30
}
return person
}
objectValue().then(console.log)
async function objectValueMulti(): Promise<Record<string, any>[]> {
const person: Record<string, any>[] = [{
name: "john doe",
age: 30
},{
name: "jane doe",
age: 30
}]
return person
}
objectValueMulti().then(console.log)类似页面
带有示例的类似页面
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