Discussion on: JavaScript Arrays: .forEach - The Functional for of loop

Thanks for the great read! It's always interesting seeing other peoples perspectives on it.

I feel like forEach is in this weird space between for of and the more functional operators map/reduce. Almost every use case for looping over an array is to change its shape, either by manipulating each item (which makes map ideal) or by aggregating the array contents (which makes reduce ideal).

Using your key/value map example, I would typically use reduce as follows:

const fruitEmojis = ['🍎', '🍌', '🍍'];
const fruitNames = ['apple', 'banana', 'pineapple'];

let fruitMap = fruitEmojis.reduce(function(map, currentFruitEmoji, index) {
  const key = fruitNames[index];
  map[key] = currentFruitEmoji;

  return map;
}, {});

console.log(fruitMap);

It's very similar, but has notably fewer side effects. You can also make it really terse, if that's your kind of thing, and if you use the spread operator to shallow copy you can reduce the footprint for unintentional side effects even further:

let fruitMap = fruitEmojis.reduce((map, current, i) => ({ 
    ...map, 
    [fruitNames[i]]: current 
}), {});

Just some thoughts. :)