button on click javascript code example

Example 1: javascript onclick

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

Example 2: how to call a function with a button in javascript

<script>
		function myFunction()
		{
			document.write("<h1>HELLO</h1>")
		}
	</script>
<button onclick="myFunction()">Click</button>

Example 3: HTML button onclick

<!DOCTYPE html>
<html>
  <head>
    <title>Title of the document</title>
  </head>
  <body>
    <p>There is a hidden message for you. Click to see it.</p>
    <button onclick="myFunction()">Click me!</button>
    <p id="demo"></p>
    <script>
      function myFunction() {
        document.getElementById("demo").innerHTML = "Hello Dear Visitor!</br> We are happy that you've chosen our website to learn programming languages. We're sure you'll become one of the best programmers in your country. Good luck to you!";
      }
    </script>
  </body>
</html>

Example 4: javascript click button by id

var button = document.getElementById("button");
button.click();

Example 5: javascript onclick

var myElem = document.getElementByID('ElemID');
myElem.onclick = function() {
	//do stuff
}

Example 6: javascript onclick button

var button = document.querySelector('button');
button.onclick = function() {
  //do stuff
}