SOURCE

var arr = [3, 1, 4, 6, 5, 7, 2];

// Array.prototype.sort
console.log(arr.sort((a,b) => a - b))

// 快排
function quickSort(arr) {
    if (!arr.length) {
        return [];
    }

    const index = Math.floor(arr.length / 2);
    const current = arr.splice(index, 1);
    const left = [];
    const right = [];

    for (let i = 0; i < arr.length; i++) {
        if (arr[i] <= current) {
            left.push(arr[i]);
        }
        else {
            right.push(arr[i]);
        }
    }

    return quickSort(left).concat(current, quickSort(right));
}

console.log(quickSort(arr));