Dev.to Aug 31 2019 Faro

aug312019.js

const split = arr => 
    [arr.slice(0, arr.length / 2), arr.slice(arr.length / 2)];

const interleave = (a, b) => 
    a.reduce((shuffled, aIdx, idx) => (shuffled.push(aIdx, b[idx]), shuffled), []);

const faro = arr => interleave(...split(arr));

/* -- Testing -- */

const assert = (exprFn, expected, msg = "Assert") => {
    try {
        const r = JSON.stringify(exprFn());
        if (r !== JSON.stringify(expected)) throw new Error(r);
    } catch(err) {
        throw new Error(`${msg}: Expected ${expected}, but got ${err.message}`);
    }
}

assert(() => faro([]), [], "Zero length");
assert(() => faro([1, 2]), [1, 2], "Two items");
assert(() => faro([1, 2, 3, 4]), [1, 3, 2, 4], "Four items");
assert(() => faro(["a", "b", "c", "d"]), ["a", "c", "b", "d"], "Four string items");
assert(() => faro(['ace', 'two', 'three', 'four', 'five', 'six']), 
    ['ace', 'four', 'two', 'five', 'three', 'six'], "Dev.to test case");