语法错误："x" 是保留标识符

¥Message

SyntaxError: Unexpected reserved word (V8-based)
SyntaxError: implements is a reserved identifier (Firefox)
SyntaxError: Cannot use the reserved word 'implements' as a variable name. (Safari)

¥Error type

¥What went wrong?

如果将它们用作标识符，则会抛出 保留关键字。这些在严格模式和宽松模式下保留：

¥Reserved keywords will throw in if they are used as identifiers. These are reserved in strict mode and sloppy mode:

• enum

以下仅当在严格模式代码中找到时才保留：

¥The following are only reserved when they are found in strict mode code:

• implements
• interface
• let
• package
• private
• protected
• public
• static

¥Examples

¥Strict and non-strict reserved keywords

enum 标识符通常被保留。

¥The enum identifier is generally reserved.

const enum = { RED: 0, GREEN: 1, BLUE: 2 };
// SyntaxError: enum is a reserved identifier

在严格模式代码中，保留了更多的标识符。

¥In strict mode code, more identifiers are reserved.

"use strict";
const package = ["potatoes", "rice", "fries"];
// SyntaxError: package is a reserved identifier

你需要重命名这些变量。

¥You'll need to rename these variables.

const colorEnum = { RED: 0, GREEN: 1, BLUE: 2 };
const list = ["potatoes", "rice", "fries"];

¥Update older browsers

例如，如果你使用的是尚未实现 let 或 class 的较旧浏览器，则应更新到支持这些新语言功能的更新浏览器版本。

¥If you are using an older browser that does not yet implement let or class, for example, you should update to a more recent browser version that does support these new language features.

"use strict";
class DocArchiver {}

// SyntaxError: class is a reserved identifier
// (throws in older browsers only, e.g. Firefox 44 and older)

¥See also

• 词汇语法