require or disallow assignment operator shorthand where possible (operator-assignment)

要求或禁止尽可能地简化赋值操作 (operator-assignment)

The --fix option on the command line can automatically fix some of the problems reported by this rule.

命令行中的 --fix 选项可以自动修复一些该规则报告的问题。

JavaScript provides shorthand operators that combine variable assignment and some simple mathematical operations. For example, x = x + 4 can be shortened to x += 4. The supported shorthand forms are as follows:

JavaScript 为变量赋值和一些简单的数学运算提供了速记运算符。例如，x = x + 4 可以简化为 x += 4。支持的简化形式如下：

 Shorthand | Separate
-----------|------------
 x += y    | x = x + y
 x -= y    | x = x - y
 x *= y    | x = x * y
 x /= y    | x = x / y
 x %= y    | x = x % y
 x <<= y   | x = x << y
 x >>= y   | x = x >> y
 x >>>= y  | x = x >>> y
 x &= y    | x = x & y
 x ^= y    | x = x ^ y
 x |= y    | x = x | y

Rule Details

This rule requires or disallows assignment operator shorthand where possible.

该规则要求或禁止尽可能地简化赋值操作

Options

This rule has a single string option:

该规则有一个字符串选项：

• "always" (default) requires assignment operator shorthand where possible
• "always" (默认) 要求尽可能地简化赋值操作
• "never" disallows assignment operator shorthand
• "never" 禁止简化赋值操作

always

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

默认选项 "always" 的 错误 代码示例：

/*eslint operator-assignment: ["error", "always"]*/

x = x + y;
x = y * x;
x[0] = x[0] / y;
x.y = x.y << z;

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

默认选项 "always" 的 正确 代码示例：

/*eslint operator-assignment: ["error", "always"]*/

x = y;
x += y;
x = y * z;
x = (x * y) * z;
x[0] /= y;
x[foo()] = x[foo()] % 2;
x = y + x; // `+` is not always commutative (e.g. x = "abc")

never

Examples of incorrect code for this rule with the "never" option:

选项 "never" 的 错误 代码示例：

/*eslint operator-assignment: ["error", "never"]*/

x *= y;
x ^= (y + z) / foo();

Examples of correct code for this rule with the "never" option:

选项 "never" 的 正确 代码示例：

/*eslint operator-assignment: ["error", "never"]*/

x = x + y;
x.y = x.y / a.b;

When Not To Use It

Use of operator assignment shorthand is a stylistic choice. Leaving this rule turned off would allow developers to choose which style is more readable on a case-by-case basis.

使用简化的赋值操作符是一个格式上的选择。关闭此规则将允许开发者在个案的基础上选择哪种风格更具可读性。

Version

This rule was introduced in ESLint 0.10.0.

该规则在 ESLint 0.10.0 中被引入。

Resources

• Rule source
• Documentation source