Disallow unmodified conditions of loops (no-unmodified-loop-condition)

禁用一成不变的循环条件 (no-unmodified-loop-condition)

Variables in a loop condition often are modified in the loop. If not, it’s possibly a mistake.

循环条件中的变量在循环中是要经常改变的。如果不是这样，那么可能是个错误。

while (node) {
    doSomething(node);
}

while (node) {
    doSomething(node);
    node = node.parent;
}

Rule Details

This rule finds references which are inside of loop conditions, then checks the variables of those references are modified in the loop.

该规则发现循环条件的引用，检查这些引用的变量在循环过程中是否发生改变。

If a reference is inside of a binary expression or a ternary expression, this rule checks the result of the expression instead.

如果一个引用是在一个二元表达式或三元表达式中，该规则改为检查表达式结果。

If a reference is inside of a dynamic expression (e.g. CallExpression, YieldExpression, …), this rule ignores it.

如果一个引用是一个动态表达式中(如 CallExpression，YieldExpression, …)，该规则将忽略这种情况。

Examples of incorrect code for this rule:

错误 代码示例：

while (node) {
    doSomething(node);
}
node = other;

for (var j = 0; j < items.length; ++i) {
    doSomething(items[j]);
}

while (node !== root) {
    doSomething(node);
}

Examples of correct code for this rule:

正确 代码示例：

while (node) {
    doSomething(node);
    node = node.parent;
}

for (var j = 0; j < items.length; ++j) {
    doSomething(items[j]);
}

// OK, the result of this binary expression is changed in this loop.
while (node !== root) {
    doSomething(node);
    node = node.parent;
}

// OK, the result of this ternary expression is changed in this loop.
while (node ? A : B) {
    doSomething(node);
    node = node.parent;
}

// A property might be a getter which has side effect...
// Or "doSomething" can modify "obj.foo".
while (obj.foo) {
    doSomething(obj);
}

// A function call can return various values.
while (check(obj)) {
    doSomething(obj);
}

When Not To Use It

If you don’t want to notified about references inside of loop conditions, then it’s safe to disable this rule.

如果你不想收到关于循环条件中引用的通知，可以禁用此规则。

Version

This rule was introduced in ESLint 2.0.0-alpha-2.

该规则在 ESLint 2.0.0-alpha-2 中被引入。

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