no-object-mutation.md

no-object-mutation

Disallow direct object-property mutation.

Rule Details

Property	Value
Type	suggestion
Fixable	No
Recommended	warn
Strict	error

Rationale

Mutating object properties in place introduces side effects and makes state transitions harder to trace. Immutable updates improve predictability.

Examples

✅ Correct

const next = { ...state, count: state.count + 1 };

class AppError extends Error {
  constructor(message: string, context?: Record<string, unknown>) {
    super(message);
    this.name = this.constructor.name;
    this.context = context;
  }
}

❌ Incorrect

state.count = state.count + 1;

Configuration

'zero-tolerance/no-object-mutation': 'error'