SOURCE

function sort(target) {
    if (!Array.isArray(nums)) throw 'not array'
    else if (target.length <= 1) return target
    const middleIndex = Math.floor(target.length / 2);
    const middleNum = target.splice(middleIndex, 1)[0];
    let left = [], right = []
    target.forEach((item) => {
        if (item < middleNum) left.push(item)
        else right.push(item)
    })
    return [...sort(left), middleNum, ...sort(right)]
}

console.log(sort([5, 1, 3, 4, 2]))