function isPrintableChar(keyCode) {
  return keyCode === 32 || // space
  keyCode >= 48 && keyCode <= 57 || // 0-9
  keyCode >= 96 && keyCode <= 111 || // numpad
  keyCode >= 186 && keyCode <= 192 || // ;=,-./`
  keyCode >= 219 && keyCode <= 222 || // []{}\|"'
  keyCode >= 226 || // special chars (229 for Asian chars)
  keyCode >= 65 && keyCode <= 90; // a-z
}
Returns true if keyCode represents a printable character.

@param {Number} keyCode
@returns {Boolean}