no-cond-assign
禁止条件表达式中的赋值运算符
在 配置文件 中使用来自 @eslint/js 的 recommended 配置可以启用此规则
在条件语句中，很容易将比较运算符（例如 ==）误键入为赋值运算符（例如 =）。例如：
¥In conditional statements, it is very easy to mistype a comparison operator (such as ==) as an assignment operator (such as =). For example:
// Check the user's job title
if (user.jobTitle = "manager") {
// user.jobTitle is now incorrect
}
在条件语句中使用赋值运算符是有充分理由的。然而，很难判断一个特定的任务是否是故意的。
¥There are valid reasons to use assignment operators in conditional statements. However, it can be difficult to tell whether a specific assignment was intentional.
规则详情
¥Rule Details
此规则不允许在 if、for、while 和 do...while 语句的测试条件中使用模棱两可的赋值运算符。
¥This rule disallows ambiguous assignment operators in test conditions of if, for, while, and do...while statements.
选项
¥Options
此规则有一个字符串选项：
¥This rule has a string option:
-
"except-parens"（默认）仅当测试条件括在括号中时才允许在测试条件中进行赋值（例如，允许在while或do...while循环的测试中重新分配变量）¥
"except-parens"(default) allows assignments in test conditions only if they are enclosed in parentheses (for example, to allow reassigning a variable in the test of awhileordo...whileloop) -
"always"不允许测试条件下的所有分配¥
"always"disallows all assignments in test conditions
except-parens
使用默认 "except-parens" 选项的此规则的错误代码示例：
¥Examples of incorrect code for this rule with the default "except-parens" option:
/*eslint no-cond-assign: "error"*/
// Unintentional assignment
var x;
if (x = 0) {
var b = 1;
}
// Practical example that is similar to an error
var setHeight = function (someNode) {
do {
someNode.height = "100px";
} while (someNode = someNode.parentNode);
}
使用默认 "except-parens" 选项的此规则的正确代码示例：
¥Examples of correct code for this rule with the default "except-parens" option:
/*eslint no-cond-assign: "error"*/
// Assignment replaced by comparison
var x;
if (x === 0) {
var b = 1;
}
// Practical example that wraps the assignment in parentheses
var setHeight = function (someNode) {
do {
someNode.height = "100px";
} while ((someNode = someNode.parentNode));
}
// Practical example that wraps the assignment and tests for 'null'
var setHeight = function (someNode) {
do {
someNode.height = "100px";
} while ((someNode = someNode.parentNode) !== null);
}
always
使用 "always" 选项的此规则的错误代码示例：
¥Examples of incorrect code for this rule with the "always" option:
/*eslint no-cond-assign: ["error", "always"]*/
// Unintentional assignment
var x;
if (x = 0) {
var b = 1;
}
// Practical example that is similar to an error
var setHeight = function (someNode) {
do {
someNode.height = "100px";
} while (someNode = someNode.parentNode);
}
// Practical example that wraps the assignment in parentheses
var setHeight = function (someNode) {
do {
someNode.height = "100px";
} while ((someNode = someNode.parentNode));
}
// Practical example that wraps the assignment and tests for 'null'
var setHeight = function (someNode) {
do {
someNode.height = "100px";
} while ((someNode = someNode.parentNode) !== null);
}
使用 "always" 选项的此规则的正确代码示例：
¥Examples of correct code for this rule with the "always" option:
/*eslint no-cond-assign: ["error", "always"]*/
// Assignment replaced by comparison
var x;
if (x === 0) {
var b = 1;
}
相关规则
版本
此规则是在 ESLint v0.0.9 中引入。