disallow the unary operators `++` and `--` (no-plusplus)

禁止使用一元操作符 `++` 和 `--` (no-plusplus)

Because the unary ++ and -- operators are subject to automatic semicolon insertion, differences in whitespace can change semantics of source code.

因为一元操作符 ++ 和 -- 会自动添加分号，不同的空白可能会改变源代码的语义。

var i = 10;
var j = 20;

i ++
j
// i = 11, j = 20

var i = 10;
var j = 20;

i
++
j
// i = 10, j = 21

Rule Details

This rule disallows the unary operators ++ and --.

该规则禁止使用一元操作符 ++ 和 --。

Examples of incorrect code for this rule:

错误代码示例：

/*eslint no-plusplus: "error"*/

var foo = 0;
foo++;

var bar = 42;
bar--;

for (i = 0; i < l; i++) {
    return;
}

Examples of correct code for this rule:

正确代码示例：

/*eslint no-plusplus: "error"*/

var foo = 0;
foo += 1;

var bar = 42;
bar -= 1;

for (i = 0; i < l; i += 1) {
    return;
}

Options

This rule has an object option.

该规则有一个对象选项。

"allowForLoopAfterthoughts": true allows unary operators ++ and -- in the afterthought (final expression) of a for loop.
"allowForLoopAfterthoughts": true 允许在 for 循环的最后一个表达式中使用 ++ 和 -- 。

allowForLoopAfterthoughts

Examples of correct code for this rule with the { "allowForLoopAfterthoughts": true } option:

选项 { "allowForLoopAfterthoughts": true } 的正确代码示例：

/*eslint no-plusplus: ["error", { "allowForLoopAfterthoughts": true }]*/

for (i = 0; i < l; i++) {
    return;
}

for (i = 0; i < l; i--) {
    return;
}

Version

This rule was introduced in ESLint 0.0.9.

该规则在 ESLint 0.0.9 中被引入。

disallow the unary operators ++ and -- (no-plusplus)