<button id="myButton" onclick="changeButtonText()">Hello</button>
function changeButtonText() {
  var button = document.getElementById("myButton");

  if (button.innerText === "Hello") {
    button.innerText = "World";
  } else {
    button.innerText = "Hello";
  }
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.