Javascript关键字列表：
break delete function return typeof
case do if switch var
catch else in this void
continue false instanceof throw while
debugger finally new true with
default for null try
Javascript未来关键字(Javascript Future Reserved Words)
Javascript还有一些未来关键字，这些字虽然现在没有用到Javascript语言中，但是将来有可能用到。
Javascript未来关键字列表：
abstract double goto native static
boolean enum implements package super
byte export import private synchronized
char extends int protected throws
class final interface public transient
const float long short volatile
