noCondAssign

Flags assignments used in conditional expressions (if, while, for condition segment).

• Category: Core (optional)
• Default: off

Config:

rules: { noCondAssign: 'warn' } // 'off' | 'warn' | 'error'

Example:

if (x = compute()) {
  // ...
}

Rationale: assignments in conditions are often mistakes; prefer explicit comparisons.

Non-violations

• Assignments outside of condition parentheses are not flagged:

let x
x = compute()
if (x) {
  // ok
}

• Comparisons in conditions are fine:

if (x === compute()) {
  // ok
}

Best practices

• Prefer explicit comparisons (===, !==) in conditions
• If you intentionally assign and test in one expression, make it obvious and consider disabling the rule locally with a comment for that line
• Split complex conditions across lines; readability reduces accidental assignments
• Consider extracting the computed value before the condition: const v = compute(); if (v) { ... }

Troubleshooting

• “It flagged a for loop” — the rule only checks the condition segment of for (init; condition; update) and will report = found in the middle segment