popup message in javascript code example

Example 1: simple alert program in javascript

alert("this is the alert")

Example 2: popup JavaScript code

document.getElementById("open-popup-btn").addEventListener("click",function(){
  document.getElementsByClassName("popup")[0].classList.add("active");
});
 
document.getElementById("dismiss-popup-btn").addEventListener("click",function(){
  document.getElementsByClassName("popup")[0].classList.remove("active");
});