ArrayToolbox

Collection of frequently useful array algorithms, mostly for use with Array.prototype.filter and Array.prototype.reduce.

Core

#### intersection
``JavaScript
ArrayToolbox.Core.intersection([1, 2, 1, 3], [1, 1, 1]);
// Returns [1, 1].
`
#### modalValues
`JavaScript
ArrayToolbox.Core.modalValues([2, 1, 1, 3, 2]);
// Returns [2, 1].
`

Filter

#### unique
`JavaScript
[2, 1, 1, 3, 2].filter( ArrayToolbox.Filter.unique());
// Returns [1, 3, 2].
`

Reduce (Accumulate)

#### defaultIfEmpty
`JavaScript
[]
.reduce( ArrayToolbox.Reduce.defaultIfEmpty(), [5])
.reduce( ArrayToolbox.Reduce.firstOrDefaultTo(), null );
// Returns 5, not null.
`
#### findAllIndexes
`JavaScript
[2, 1, 1, 3, 2].reduce( ArrayToolbox.Reduce.findAllIndexes( 2 ), []);
// Returns [0, 4].
`
#### firstOrDefaultTo
`JavaScript
// Get minimum value of an array of objects.
let collator_comparator = function( left, right )
{return( this.compare( left.value, right.value ));}
.bind( new Intl.Collator([], {"numeric":true}));
let array =
[
{"value":5},
{"value":3},
{"value":4}
];
array
.sort( collator_comparator )
.reduce( ArrayToolbox.Reduce.firstOrDefaultTo(), null );
// Returns {"value":3}.
`
#### lastOrDefaultTo
`JavaScript
// Get maximum value of an array of objects.
let collator_comparator = function( left, right )
{return( this.compare( left.value, right.value ));}
.bind( new Intl.Collator([], {"numeric":true}));
let array =
[
{"value":5},
{"value":3},
{"value":4}
];
array
.sort( collator_comparator )
.reduce( ArrayToolbox.Reduce.lastOrDefaultTo(), null );
// Returns {"value":5}.
`
#### singleOrDefaultTo
`JavaScript
// Assert array is empty or contains only one element.
let array =
[
{"value":5},
{"value":3},
{"value":4}
];
array
.filter( function( each, n, every )
{return( each.value > 3 );})
.reduce( ArrayToolbox.Reduce.singleOrDefaultTo(), null );
// Throws RangeError: 'array' should be of length 0 or 1..
``