You want your code to execute only once your page has finished loading. For that purpose, you can attach a JavaScript event to the document called DOMContentLoaded. Here's the code that does this:
document.addEventListener('DOMContentLoaded', function() {
});
You can implement event handlers that go inside of the DOMContentLoaded function. You can implement an onclick event handler which triggers when the user clicks on the #getMessage element, by adding the following code:
document.getElementById('getMessage').onclick = function(){};
Add a click event handler inside of the DOMContentLoaded function for the element with id of getMessage.
Waiting: Your code should use the document.getElementById method to select the element whose id is getMessage. Waiting: Your code should add an onclick event handler.