What's the best way to automatically insert slashes '/' in date fields

Question

I\'m trying to add functionality to input date fields so as when the users enters in digits, slashes \"/\" get automatically added.

So suppose I have the following

Answer 1

I spent some time working on the solution that Chris posted above and am accounting for everything except pasting, which isn't a requirement from the original poster as I read it.

//Bind keyup/keydown to the input
$('.date').bind('keyup', 'keydown', function(e) {
  //check for numerics
  var thisValue = $(this).val();
  thisValue = thisValue.replace(/[^0-9\//]/g, '');
  //get new value without letters
  $(this).val(thisValue);
  thisValue = $(this).val();
  var numChars = thisValue.length;
  $('#keyCount').html(numChars);
  var thisLen = thisValue.length - 1;
  var thisCharCode = thisValue.charCodeAt(thisLen);
  $('#keyP').html(thisCharCode);
  //To accomdate for backspacing, we detect which key was pressed - if backspace, do nothing:
  if (e.which !== 8) {
    if (numChars === 2) {
      if (thisCharCode == 47) {
        var thisV = '0' + thisValue;
        $(this).val(thisV);
      } else {
        thisValue += '/';
        $(this).val(thisValue);
      }
    }
    if (numChars === 5) {
      if (thisCharCode == 47) {
        var a = thisValue;
        var position = 3;
        var output = [a.slice(0, position), '0', a.slice(position)].join('');
        $(this).val(output);
      } else {
        thisValue += '/';
        $(this).val(thisValue);
      }
    }
    if (numChars > 10) {
      var output2 = thisValue.slice(0, 10);
      $(this).val(output2);
    }
  }
});
$('.date').blur(function() {
  var thisValue = $(this).val();
  var numChars = thisValue.length;
  if (numChars < 10) {
    $(this).addClass('brdErr');
    $('#dateErr1').slideDown('fast');
    $(this).select();
  } else {
    $(this).removeClass('brdErr');
    $('#dateErr1').hide();
  }
});

There is a lot added and a CSS class for an error message for invalid dates.

JSFiddle Here