no-cond-assign

配置文件中的"extends": "eslint:recommended"属性启用此规则。

在条件语句中，将比较运算符（如==）作为赋值运算符（例如=）输错是非常容易的。例如：

// 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正当理由的。但是，可能很难判断具体的任务是否是故意的。

规则细节

这条规则不允许在试验条件不明确赋值运算符if，for，while，和do...while语句。

选项

这条规则有一个字符串选项：

"except-parens"（缺省值）只允许在测试条件下进行赋值，如果它们被括在圆括号中（例如，允许在while或do...while循环的测试中重新赋值变量）

"always" 不允许在测试条件下的所有分配

除了-双亲

此规则的默认"except-parens"选项错误代码示例：

/*eslint no-cond-assign: "error"*/

// Unintentional assignment
var x;
if (x = 0) {
    var b = 1;
}

// Practical example that is similar to an error
function setHeight(someNode) {
    "use strict";
    do {
        someNode.height = "100px";
    } while (someNode = someNode.parentNode);
}

具有默认"except-parens"选项的此规则的正确代码示例：

/*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
function setHeight(someNode) {
    "use strict";
    do {
        someNode.height = "100px";
    } while ((someNode = someNode.parentNode));
}

// Practical example that wraps the assignment and tests for 'null'
function setHeight(someNode) {
    "use strict";
    do {
        someNode.height = "100px";
    } while ((someNode = someNode.parentNode) !== null);
}

总是

包含以下"always"选项的此规则的错误代码示例：

/*eslint no-cond-assign: ["error", "always"]*/

// Unintentional assignment
var x;
if (x = 0) {
    var b = 1;
}

// Practical example that is similar to an error
function setHeight(someNode) {
    "use strict";
    do {
        someNode.height = "100px";
    } while (someNode = someNode.parentNode);
}

// Practical example that wraps the assignment in parentheses
function setHeight(someNode) {
    "use strict";
    do {
        someNode.height = "100px";
    } while ((someNode = someNode.parentNode));
}

// Practical example that wraps the assignment and tests for 'null'
function setHeight(someNode) {
    "use strict";
    do {
        someNode.height = "100px";
    } while ((someNode = someNode.parentNode) !== null);
}

包含以下"always"选项的此规则的正确代码示例：

/*eslint no-cond-assign: ["error", "always"]*/

// Assignment replaced by comparison
var x;
if (x === 0) {
    var b = 1;
}

规则细节

选项

除了-双亲

总是

相关规则