no-cond-assign.md

Pattern: Assignment operator in conditional expression

Issue: -

Description

Using assignment operators (=) in conditional expressions is often a typo for comparison operators (==, ===). While there are valid use cases for assignment in conditions, it frequently indicates a mistake that can lead to unexpected behavior.

Examples

Example of incorrect code:

if ((user.jobTitle = "manager")) {
  // user.jobTitle is now "manager" instead of comparing
}

while (nextItem = getNextItem()) {
  // ...
}

Example of correct code:

if (user.jobTitle === "manager") {
  // comparison, not assignment
}

let nextItem;
while ((nextItem = getNextItem()) !== null) {
  // explicit parentheses show assignment is intentional
}