mu-unique

Uniqueify an array of elements.

Runtime complexity: O(n*log(n)) for sortable arrays, O(n^2) for non-sortable arrays.

unique(arr, sortable, comparator)

0. arr {Array} - The source array.
1. sortable {Boolean} - Optional. Does the array contain sortable elements? defaults to false.
2. comparator {Function} - Optional.
   • If the array is sortable, it defines the order of the elements in the array. It is called with 2 elements from the array and should return 0 if they are equal, a positive number if a is bigger and a negative number if b is bigger. If not provided, the array will be sorted with a natural order (as defined by the runtime).
   • If the array is not sortable, it defines the equality between elements in the array. It is called with 2 elements from the array and should return true if they are equal, and false otherwise. If not provided, the elements will be tested for equality with ===.

Notes:

0. The function modifies the array and returns its new length.
1. The original order of items may not be preserved.
2. If the this value of the function is defined, it will be used as the array (see examples). Thus it is possible to use this function to extend the Array prototype: Array.prototype.unique = unique.

Installation

• Node: 0. npm install mu-unique 0. var unique = require('mu-unique');
• AMD (install with bower): 0. bower install mu-unique 0. require(['mu-unique'], function(unique){ /* ... */ });

Run tests with make test.

Run coverage analysis with make coverage (coverage report is saved to ./coverage).

Examples

var arr = [1, 2, 1, 2, 3],
    len = unique(arr);
console.log(arr, true); // [1, 2, 3]
console.log(len); // 3

var o1 = {},
    o2 = function(){},
    o3 = "foo",
    arr = [o1,o1,o2,o3,o2,o3],
    len = unique(arr);
console.log(arr); // [o1, o2, o3]
console.log(len); // 3

With a custom order:

var arr1 = ['hello', 'hi', 'world'],
    arr2 = unique(arr1, function(a, b){
        // compare only first character
        return a[0] > b[0] ? 1 : a[0] < b[0] ? -1 : 0; 
    });
console.log(arr1); // ['hello', 'hi', 'world']
console.log(arr2); // ['hello', 'world']

By setting the this value:

var arr = [1, 2, 1, 2, 3],
    len = unique.call(arr);
console.log(arr); // [1, 2, 3]
console.log(len); // 3