function quicksort(arr){
var temp = Number(arr[0]),
leftArr = [],
rightArr = [];
for(var i = 1, len = arr.length;i < len;i++){
if(Number(arr[i]) - temp < 0) leftArr.push(arr[i])
else rightArr.push(arr[i])
}
if(arr.length <= 1) return arr
return [].concat(quicksort(leftArr), temp, quicksort(rightArr))
}
var arr = quicksort([9, 5, 7, 2,6, 10, 4])
console.log(arr)