1.通用保留关键字
| 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 |
2.ECMAScript 5 增加保留
| class | const | enum | export | extends |
| import | super |
3.普通下合法，但严格模式下是保留的
| implements | let | private | public | yield |
| interface | package | protected | static |
4.严格模式下做了严格限制，并不完全是保留字，但不能用作变量名，函数名或参数名
| arguments | eval |
5.ECMAScript3关键字
| 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 |
6.Javascript预定义了很多全局变量和函数，应当避免把它们的名字用做变量名和函数名:
| arguments | encodeURI | Infinity | Number | RegExp |
| Array | encodeURIComponent | isFinite | Object | String |
| Boolean | Error | isNaN | parseFloat | SyntaxError |
| Date | eval | JSON | parseInt | TypeError |
| decodeURI | EvalError | Math | RangeError | undefined |
| decodeURIComponent | Function | NaN | ReferenceError | URIError |