TypeScript

npm i -g typescript

Set-ExecutionPolicy RemoteSigned

tsc script

tsc --init

tsc

const a = 3;
const b = '5';
console.log(a*b)

const a:number = 3;
const b:string = '5';
console.log(a*b)

var alist = document.querySelectorAll('a');
for (var i = 0; i < alist.length; i++) {
  alist[i].style.color = '#333'
};

var example = document.querySelector('.exampleClass');
example.style.backgroundColor = "#ccc";

document.addEventListener('mousemove', function () {
  var x = event.clientX;
  document.querySelector('h1').style.fontSize = (x / 50) + 'px'
});

const alist = document.querySelectorAll('a');
for (let i: number = 0; i < alist.length; i++) {
  alist[i].style.color = '#333'
};

const example: HTMLElement = document.querySelector('.exampleClass');
example.style.backgroundColor = "#ccc";

document.addEventListener('mousemove', function (event: MouseEvent) {
  const x = event.clientX;
  (document.querySelector('h1') as HTMLElement).style.fontSize = String(x / 50) + 'px';
});