add a onclick event in javascript code example

Example 1: javascript onclick event listener

document.getElementById("myBtn").addEventListener("click", function() {
  alert("Hello World!");
});

Example 2: how to add onclick event in javascript

var element = document.getElementById("elem");
element.onclick = function(event) {
  console.log(event);
}

Example 3: javascript onclick

document.getElementById("Save").onclick = function ()
    {
     alert("hello");
     //validation code to see State field is mandatory.  
    }