Format HTML input on the fly (require jQuery)

auto-format.js

$container.on('keyup', '.auto-formatted', function(e) {
  var val = $(this).val();
  var pureVal = parseFloat(util.unformat(val));

  if (isValid(pureVal)) { // isNaN if number
    $(this).data('val', defaultVal); // 0 if number
    return;
  }
  $(this).data('val', pureVal);
  var newVal = util.format(pureVal);
  
  // preserve cursor position/selection
  var lengthDiff = newVal.length - val.length;
  var start = this.selectionStart + lengthDiff,
      end = this.selectionEnd + lengthDiff;
  $(this).val(newVal);
  this.setSelectionRange(start, end);
});