Add function to button, javascript code example

Example 1: javascript button

<button onclick="Function()">Text</button>

Example 2: javascript click event

<button onclick="myFunction()">Click me</button>

<p id="demo"></p>

<script>
function myFunction() {
  document.getElementById("demo").innerHTML = "Hello World";
}
</script>

Example 3: javascript onclick

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