binding event isused to get notified when event occurs code example

Example 1: handling event changes

<button>Act-once button</button>
<script>
  let button = document.querySelector("button");
  function once() {
    console.log("Done.");
    button.removeEventListener("click", once);
  }
  button.addEventListener("click", once);
</script>

Example 2: handling event changes

<p>Press Control-Space to continue.</p>
<script>
  window.addEventListener("keydown", event => {
    if (event.key == " " && event.ctrlKey) {
      console.log("Continuing!");
    }
  });
</script>