How can I check the new value of a text field on keypress?

Question

I have a single form field and I need to be able to detect when the field changes and execute some additional code using the new value of the field. I only want to execute the code if the key pushed actually changes the value of the text box. Here's the solution I came up with.

function onkeypress(e) {
  var value = this.value;
  // do something with 
}

function onkeyup(e) {
  if ( e.which == 8 || e.keyCode == 46 ) { // delete or backspace keys
    this.onkeypress(e);
  }
}

There's just one problem though. onkeypress is fired before the field's value is updated, so when I grab the value, I'm getting the previous value. I would use keyup exclusively if I knew a way to test whether the key changed the value or not, but some characters (like the arrow keys) have no effect on the field's value.

Any ideas?

Answer 1

this is easy, just use onkeyup instead of onkeypress