JavaScript 的保留关键字不可以用作变量、标签或者函数名。有些保留关键字是作为 Javascript 以后扩展使用。
abstract | arguments | boolean | break | byte |
case | catch | char | class* | const |
continue | debugger | default | delete | do |
double | else | enum* | eval | export* |
extends* | false | final | finally | float |
for | function | goto | if | implements |
import* | in | instanceof | int | interface |
let | long | native | new | null |
package | private | protected | public | return |
short | static | super* | Switch | synchronized |
this | throw | throws | transient | true |
try | typeof | var | void | volatile |
while | with | yield |
* 标记的关键字是 ECMAScript5 中新添加的。