Bored on a bus...

quicksort.js

// Being bored on a bus
// Simple quickSort, always take index zero as the pivot

var unsorted = [3, 5, 1, 7, 6, 7, 3];

function generateChallengeArray(length, max){
  var arr = [];
  for(var i = 0; i < length; i++){
    arr.push(Math.random()*max);
  }
  return arr;
}

function quickSort(arr){
  if(arr.length === 1 || arr.length === 0){
    return arr;
  }
  var greater = [];
  var less = [];
  for(var i = 1; i < arr.length; i++){
    if(arr[i] >= arr[0]) greater.push(arr[i]);
    else less.push(arr[i]);
  }
  return arrayConcat(quickSort(less), arr[0], quickSort(greater));
}
function arrayConcat(arr1, val, arr2){
  // This is faster than array.concat, because concat will allocate an entirely new array in memory
  arr1.push(val);
  for(var i = 0; i < arr2.length; i++){
    arr1.push(arr2[i]);
  }
  return arr1;
}
unsorted = generateChallengeArray(10000000, 1000);
console.log("generated");
var time = Date.now();
var arr = quickSort(unsorted);
console.log("That took " + (Date.now() - time)/1000 + " seconds");
console.log("verifying...");
for(var i = 1; i < arr.length; i++){
  if(arr[i] < arr[i-1]){
    console.log("FAILED!");
  }
}
console.log("PASSED!")