type of typescript
// Prints "string"
console.log(typeof "Hello world");type of typescript
// Prints "string"
console.log(typeof "Hello world");custom types in typescript
// 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 type definition
// 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)use type as value typescript
Typescript interfaces aren''t being compiled into the js output, and you can not use them at runtimeCopyright © 2021 Codeinu
Forgot your account's password or having trouble logging into your Account? Don't worry, we'll help you to get back your account. Enter your email address and we'll send you a recovery link to reset your password. If you are experiencing problems resetting your password contact us
