​x
 
<!DOCTYPE html>
<html>
<body>
​
<h2>JavaScript Promise</h2>
​
<p>Wait 3 seconds (3000 milliseconds) for this page to change.</p>
​
<h1 id="demo"></h1>
​
<script>
const myPromise = new Promise(function(myResolve, myReject) {
  setTimeout(function(){ myResolve("I love You !!"); }, 3000);
});
​
myPromise.then(function(value) {
  document.getElementById("demo").innerHTML = value;
});
</script>
​
</body>
</html>
​