Question

i have a code here triggered by an onkeypress… i want it to alert whenever there is a special character typed. Aside from an alert, if the user will type a special character in a field, the typed special character should be erased and the focus should go back to the field. I can’t seem to shake this problem. Can you help me? thanks in advance 😀

function ei(e)
{
  var iChars = "!@#$%^&*()+=-[]\\\';,./{}|\":<>?";
  for (var i = 0; i < e.value.length; i++) {
    if (iChars.indexOf(e.value.charAt(i)) != -1) {
      alert ("Please do not use special characters.");
      e.value = e.value-1;
      e.focus();
      return false;
    }
  }
}

this will be called in text field.. like this

<input type="text" name="name" onkeyup="ei(this)">

Answer 1

Why would you bother using the keyup event? It’d be better off using the keydown or keypress event and then cancelling it (I used this site to find the keycodes):

function ei (event) {
    event = event || window.event;

    switch (event.keyCode) {
        case 47: //.
        case 33: //!
        //etc
            event.preventDefault(); //cancel the current action, which will stop it writing out to the textbox
            break;
        default:
            break;
    }
}

I would also suggest you look into jQuery rather than having inline JavaScript to hook up your events and also take a look at the jQuery Validation plugin as that should help take care of a lot of your code.