Disallow unmodified loop conditions
Variables in a loop condition often are modified in the loop. If not, it’s possibly a mistake.
while (node) {
doSomething(node);
}
while (node) {
doSomething(node);
node = node.parent;
}
This rule finds references which are inside of loop conditions, then checks the variables of those references are modified in the loop.
If a reference is inside of a binary expression or a ternary expression, this rule checks the result of the expression instead. If a reference is inside of a dynamic expression (e.g. CallExpression
, YieldExpression
, …), this rule ignores it.
Examples of incorrect code for this rule:
/*eslint no-unmodified-loop-condition: "error"*/
var node = something;
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:
/*eslint no-unmodified-loop-condition: "error"*/
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);
}
If you don’t want to notified about references inside of loop conditions, then it’s safe to disable this rule.
This rule was introduced in ESLint v2.0.0-alpha-2.
© OpenJS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/latest/rules/no-unmodified-loop-condition