Arrays & Array Methods (map, filter, reduce)

const data = [1, null, 3, undefined, 5];
const result = data
  .filter(x => x != null)
  .map(x => x * 2)
  .filter(x => x > 5);

Remove zero values
Remove null and undefined values
The first filter removes null and undefined: 1) x != null checks for both null and undefined due to loose equality, 2) Ensures clean data for subsequent operations, 3) Prevents TypeError in calculations, 4) Common pattern for data sanitization, 5) More concise than explicit null/undefined checks, 6) Maintains array structure for valid elements, 7) Important for robust data processing, 8) Best practice for handling potentially incomplete data.
Remove negative numbers
Remove even numbers