JS保留字

• 他们不能被用来命名变量和参数。
  (```)
  abstract
  boolean
  break
  byte
  case
  catch
  class
  const
  continue
  debugger
  default
  delete
  do
  double
  else
  enum
  export
  extends
  false
  finnal
  finally
  float
  for
  function
  goto
  if
  implements
  import
  in
  instanceof
  int
  interface
  long
  native
  new
  null
  package
  private
  protected
  public
  return
  short
  static
  super
  switch
  synchronized
  this
  throw
  throws
  transient
  true
  try
  typeof
  var
  volatile
  void
  while
  with

(```)