Using the Keypress Event (3)

We introduced the JavaScript 1.2 switch statement in column 19. It is particularly suited to keypress handling, since we can simply list our "hot" keys in a lookup-table-like fashion, and use the default: label for any non-"hot" key processing.

function doKey(e) {
  whichASC = (NS4) ? e.which : event.keyCode;
  whichKey = String.fromCharCode(whichASC).toLowerCase();

  switch (whichKey) {
    case "a":
      doA();
      break;
    case "b":
      doB();
      break;
    case "1":
      location.href = "page1.html";
      break;
    case "2":
      location.href = "page2.html";
      break;
    case "y":
      alert('You answered "Yes"')
      break;
    case "n":
      alert('You answered "No"')
      break;
    default:
      break;
  }
}

In the example above, we have defined statements to be executed whenever a, b, y, and n (regardless of case) and 1 and 2 are pressed.

Notice that upon keypress, we may choose to execute a function, navigate to a new page, or display an alert window. Any normal JavaScript statements may be included. In this page's live example (left column), keypresses toggle the state of form checkboxes.

On the next page, a quick review of the code necessary for using the keypress event.