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# JavaScript Quick Sort Array Proto Type Method

, 18 Jul 2014 CPOL 3.5K
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## Introduction

This is a proto type method for arrays in JavaScript. It utilizes an iterative version of the Quick Sort algorithm. More information about the quick sort algorithm can be found here.

## Background

I adapted an iterative version of Quick Sort made in C located here. I tested this iterative version and a recursive version and found that the iterative version usually preforms about twice as fast. I also included some additional features that are not included in the vanilla version of JavaScript sort.

## JavaScript Quick Sort Library

```(function()
{
var
defaultCompare,
defaultSwap,
partition,
quickSort;

Array.prototype.quickSort = function(compare, swap)
{
if (typeof compare !== "function")
{
compare = defaultCompare;
}
if (typeof swap !== "function")
{
swap = defaultSwap;
}
quickSort(this, 0, this.length - 1, compare, swap);
};
defaultCompare = function(value1, value2)
{
return value1 < value2;
};
defaultSwap = function(array, index1, index2)
{
var temp = array[index1];
array[index1] = array[index2];
array[index2] = temp;
};
partition = function(array, start, stop, compare, swap)
{
var pivot = array[stop], storeIndex = start - 1;

while (start < stop)
{
if (compare(array[start], pivot))
{
storeIndex++;
swap(array, storeIndex, start);
}
start++;
}
swap(array, storeIndex + 1, stop);
return storeIndex + 1;
};
quickSort = function(array, startIndex, stopIndex, compare, swap)
{
var pivot, stack, start, top;

stack = new Array(stopIndex - startIndex + 1);
top = -1;

stack[++top] = startIndex;
stack[++top] = stopIndex;

while (top > -1)
{
stopIndex = stack[top--];
startIndex = stack[top--];

pivot = partition(array, startIndex, stopIndex, compare, swap);

if (pivot - 1 > startIndex)
{
stack[++top] = startIndex;
stack[++top] = pivot - 1;
}

if (pivot + 1 < stopIndex)
{
stack[++top] = pivot + 1;
stack[++top] = stopIndex;
}
}
};
}());```

## Using the libary

These examples explain how to use this code.

```//
//Plain Sort
//
var plainSort = [4, 7, 6, 5, 7, 0, 1, 5, 10, 10, 8];
plainSort.quickSort();
console.log(JSON.stringify(plainSort));
//Prints: [0,1,4,5,5,6,7,7,8,10,10]

//
//Sort With Custom Compare Function
//
var descendingOrder = [4, 7, 6, 5, 7, 0, 1, 5, 10, 10, 8];
descendingOrder.quickSort(function(a, b)
{
//Descending order compare
return a > b;
});
console.log(JSON.stringify(descendingOrder));
//Prints: [10,10,8,7,7,6,5,5,4,1,0]

//
//Sort multiple arrays with a custom compare
//
var table =
{
"employeeName": ["Jane", "John", "Tom", "Alex", "Mary"],
"id": [10, 5, 7, 3, 0]
};
table.employeeName.quickSort(function(a, b)
{
//Strings have to be compared using the localeCompare function
return (a || "").localeCompare(b) < 0;
},
function(array, index1, index2)
{
//Sorts both arrays in the 'table' object
var temp = array[index1];
array[index1] = array[index2];
array[index2] = temp;

temp = table.id[index1];
table.id[index1] = table.id[index2];
table.id[index2] = temp;
});
console.log(JSON.stringify(table));
//Prints:{"employeeName":["Alex","Jane","John","Mary","Tom"],"id":[3,10,5,0,7]} ```

## About the Author

 United States
No Biography provided

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