TypeScript Demo code

app.ts

// DOM Elements

const addBtn = document.getElementById("add-btn");
const number1 = document.getElementById("num1")! as HTMLInputElement;
const number2 = document.getElementById("num2")! as HTMLInputElement;

// function to add two numbers and return the result
function addNum(num1:number, num2:number): number {
    return num1 + num2;
}

// event listener for add button
addBtn.addEventListener("click", function() {
    console.log(addNum(parseInt(number1.value), parseInt(number2.value)))
})