prefer-for-of-loops-over-array-methods

Summary

Prefer native for (const item of items) loops over Array methods like forEach. While map and filter are acceptable for simple transformations, forEach should never be used.

Rationale

• Debugging: forEach callbacks create new stack frames, making "Step Over" debugging difficult (it steps into the callback or finishes the loop entirely). for-of keeps execution in the current scope.
• Performance: for-of is generally faster as it avoids the function call overhead for every element.
• Control Flow: forEach does not support await, break, or continue in a standard way. for-of handles these naturally.

Guidance

1. Strict Ban: Do not use Array.prototype.forEach. Always replace it with for-of.
2. Preference: Use for-of for any logic involving side effects, asynchronous await, or complex bodies.
3. Exceptions:
   • One-Liners: Simple map and filter chains are allowed for pure data transformations (e.g., const names = users.map(u => u.name)).
   • If the transformation becomes complex or multi-line, prefer for-of with an explicit accumulator.

Examples