qsort

qsort.js

function qsort(arr){
    if(arr.length < 2)return arr;
    var p = arr.shift(), qa = [], qb = [];
    for(var i = 0, l = arr.length; i < l; i++){
        if(p >= arr[i]) qa.push(arr[i]);
        if(p < arr[i]) qb.push(arr[i]);
    }
    return qsort(qa).concat([p]).concat(qsort(qb));
}
qsort([6,7,8,9,0,1,2,3]);