nonblock-statement-body-position

强制执行单行语句的位置

在编写 if、else、while、do-while 和 for 语句时，主体可以是单个语句而不是块。为这些单个语句强制执行一致的位置可能很有用。

¥When writing if, else, while, do-while, and for statements, the body can be a single statement instead of a block. It can be useful to enforce a consistent location for these single statements.

例如，一些开发者避免编写这样的代码：

¥For example, some developers avoid writing code like this:

if (foo)
  bar();
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如果其他开发者尝试将 baz(); 添加到 if 语句中，他们可能会错误地将代码更改为

¥If another developer attempts to add baz(); to the if statement, they might mistakenly change the code to

if (foo)
  bar();
  baz(); // this line is not in the `if` statement!
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为避免此问题，可能需要所有单行 if 语句直接出现在条件之后，没有换行符：

¥To avoid this issue, one might require all single-line if statements to appear directly after the conditional, without a linebreak:

if (foo) bar();
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规则详情

¥Rule Details

此规则旨在为单行语句强制执行一致的位置。

¥This rule aims to enforce a consistent location for single-line statements.

请注意，此规则通常不强制使用单行语句。如果你想禁止单行语句，请改用 curly 规则。

¥Note that this rule does not enforce the usage of single-line statements in general. If you would like to disallow single-line statements, use the curly rule instead.

选项

¥Options

此规则接受字符串选项：

¥This rule accepts a string option:

• "beside"（默认）不允许在单行语句之前出现换行符。

  ¥"beside" (default) disallows a newline before a single-line statement.

• "below" 在单行语句之前需要换行符。

  ¥"below" requires a newline before a single-line statement.

• "any" 不强制单行语句的位置。

  ¥"any" does not enforce the position of a single-line statement.

此外，该规则接受带有 "overrides" 键的可选对象选项。这可用于指定覆盖默认值的特定语句的位置。例如：

¥Additionally, the rule accepts an optional object option with an "overrides" key. This can be used to specify a location for particular statements that override the default. For example:

• "beside", { "overrides": { "while": "below" } } 要求所有单行语句与其父语句出现在同一行，除非父语句是 while 语句，在这种情况下，单行语句不得位于同一行。

  ¥"beside", { "overrides": { "while": "below" } } requires all single-line statements to appear on the same line as their parent, unless the parent is a while statement, in which case the single-line statement must not be on the same line.

• "below", { "overrides": { "do": "any" } } 不允许所有单行语句与其父语句出现在同一行，除非父语句是 do-while 语句，在这种情况下，不强制执行单行语句的位置。

  ¥"below", { "overrides": { "do": "any" } } disallows all single-line statements from appearing on the same line as their parent, unless the parent is a do-while statement, in which case the position of the single-line statement is not enforced.

使用默认 "beside" 选项的此规则的错误代码示例：

¥Examples of incorrect code for this rule with the default "beside" option:

/* eslint nonblock-statement-body-position: ["error", "beside"] */

if (foo)
  bar();
else
  baz();

while (foo)
  bar();

for (let i = 1; i < foo; i++)
  bar();

do
  bar();
while (foo)

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使用默认 "beside" 选项的此规则的正确代码示例：

¥Examples of correct code for this rule with the default "beside" option:

/* eslint nonblock-statement-body-position: ["error", "beside"] */

if (foo) bar();
else baz();

while (foo) bar();

for (let i = 1; i < foo; i++) bar();

do bar(); while (foo)

if (foo) { // block statements are always allowed with this rule
  bar();
} else {
  baz();
}
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使用 "below" 选项的此规则的错误代码示例：

¥Examples of incorrect code for this rule with the "below" option:

/* eslint nonblock-statement-body-position: ["error", "below"] */

if (foo) bar();
else baz();

while (foo) bar();

for (let i = 1; i < foo; i++) bar();

do bar(); while (foo)
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使用 "below" 选项的此规则的正确代码示例：

¥Examples of correct code for this rule with the "below" option:

/* eslint nonblock-statement-body-position: ["error", "below"] */

if (foo)
  bar();
else
  baz();

while (foo)
  bar();

for (let i = 1; i < foo; i++)
  bar();

do
  bar();
while (foo)

if (foo) {
  // Although the second `if` statement is on the same line as the `else`, this is a very common
  // pattern, so it's not checked by this rule.
} else if (bar) {
}
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此规则与 "beside", { "overrides": { "while": "below" } } 规则的错误代码示例：

¥Examples of incorrect code for this rule with the "beside", { "overrides": { "while": "below" } } rule:

/* eslint nonblock-statement-body-position: ["error", "beside", { "overrides": { "while": "below" } }] */

if (foo)
  bar();

while (foo) bar();
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此规则与 "beside", { "overrides": { "while": "below" } } 规则的正确代码示例：

¥Examples of correct code for this rule with the "beside", { "overrides": { "while": "below" } } rule:

/* eslint nonblock-statement-body-position: ["error", "beside", { "overrides": { "while": "below" } }] */

if (foo) bar();

while (foo)
  bar();
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何时不使用

¥When Not To Use It

如果你不关心单行语句的位置一致，则不应启用此规则。如果你对 curly 规则使用 "all" 选项，你也可以禁用此规则，因为这将完全禁止单行语句。

¥If you’re not concerned about consistent locations of single-line statements, you should not turn on this rule. You can also disable this rule if you’re using the "all" option for the curly rule, because this will disallow single-line statements entirely.

版本

此规则是在 ESLint v3.17.0 中引入。

进阶读物

JSCS
jscs-dev.github.io

资源

• 规则源码
• 测试源码