Shorten codes with the comma operator

const c = (a, b);

let result;
if (condition) {
    doSomething();
    result = value;
} else {
    result = other;
}

// Shorten version
const result = condition ? (doSomething(), value) : other;

const arrowFn = (arg) => {
    doSomething();
    return result;
};

// Shorten version
const arrowFn = (arg) => (doSomething(), result);

const countOccurrences = (arr) => arr.reduce((p, c) => ((p[c] = ++p[c] || 1), p), {});

countOccurrences([2, 1, 3, 3, 2, 3]);
// { '1': 1, '2': 2, '3': 3 }

const chunk = (arr, s) => arr.reduce((a, e, i) => (i % s ? a[a.length - 1].push(e) : a.push([e]), a), []);

chunk([1, 2, 3, 4, 5, 6, 7, 8], 3);
// [[1, 2, 3], [4, 5, 6], [7, 8]]