typescript variable declaration code example

Example 1: how to declare variable in typescript

const variableSample: number = 0;
let variableSample: number = 0;

Example 2: declare and initialize variable in typescript

var name:string = "John"; 
var score1:number = 50;
var score2:number = 42.50
var sum = score1 + score2

Example 3: typescript type declaration

// 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)

Example 4: variable declare in ts

let a:number =1
let b:Boolean = true
let c:string = "Grepper"