@parellin/lightmap

Fast Map extension for Node.js & The Browser

LightMap

LightMap is an extension of Map that adds iterative extensions to Map like map, filter, reduce, sort, etc.

Installation

npm i @parellin/lightmap

Usage

Basic usage:

const LightMap = require( '@parellin/lightmap' );

const x = new LightMap( [ [ 'a', 'hello' ], [ 'b', 'world' ] ] );
// LightMap { 'a' => 'hello', 'b' => 'world' }

Map usage:

For standard Map usage please refer to MDN Web Docs

.filter:

Filter LightMap based on keys and values based in. Comparisons can be made on the key and/or value.

const x = new LightMap( [ [ 'a', 'hello' ], [ 'b', 'world' ] ] );

x.filter( ( val, key ) => {
	return key === 'a';
} );
// LightMap { 'a' => 'hello' }

.map:

Map LightMap with new key and/or value. Return the new item in a "tuple" form matching the Map paradigm ([ x, y ]).

const x = new LightMap( [ [ 'a', 10 ], [ 'b', 20 ] ] );

x.map( ( val, key ) => {
	return [ key, val + 10 ];
} );
// LightMap { 'a' => 20, 'b' => 30 }

.reduce:

Reduce LightMap with new value. Must return the carriage value just like Array.reduce.

const x = new LightMap( [ [ 'a', 'hello' ], [ 'b', 'world' ] ] );

x.reduce( ( r, [ key, val ] ) => {
	r += val + ' ';
	return r;
}, '' );
// hello world 

.sortKeys:

Map LightMap with sorted key-value pairs.

const x = new LightMap( [ [ 'b', 'world' ], [ 'a', 'hello' ] ] );

x.sortKeys()
// LightMap { 'a' => 'hello', 'b' => 'world' }

.sortValues:

Map LightMap with sorted key-value pairs sorted by value.

const x = new LightMap( [ [ 'a', 10 ], [ 'b', 5 ], [ 'c', 1 ] ] );

x.sortValues( ( a, b ) => a >= b )
// LightMap { 'c' => 1, 'b' => 5, 'a' => 10 }

x.sortValues( ( a, b ) => a <= b )
// LightMap { 'a' => 10, 'b' => 5, 'c' => 1 }

.mapToArray:

maps a LightMap object to an array of arrays in the Map Pattern (re-constructable pattern)

const x = new LightMap( [ [ 'a', 0 ], [ 'b', 1 ] ] );

x.mapToArray();
// [ [ 'a', 0 ], [ 'b', 1 ] ]

.toJSON:

Native class override - returns .mapToArray method

const x = new LightMap( [ [ 'a', 0 ], [ 'b', 1 ] ] );

x.toJSON();
// [ [ 'a', 0 ], [ 'b', 1 ] ]

.toString:

Native class override - returns JSON stringified .mapToArray

const x = new LightMap( [ [ 'a', 0 ], [ 'b', 1 ] ] );

x.toString();
// [["a",0],["b",1]]

.indexOf:

returns the first index at which a given element can be found in the array, or -1 if it is not present

const x = new LightMap( [ [ 'a', 0 ], [ 'b', 1 ] ] );

x.indexOf( 'b' );
// 1

[ Symbol.replace ]:

symbol specifies the method that replaces matched substrings of a string

const x = new LightMap( [ [ '{{ a }}', 'hello' ], [ '{{ b }}', 'world' ] ] );

'{{ a }} {{ b }}'.replace( x );
// hello world

[ Symbol.toPrimitive( string ) ]:

symbol that specifies a function valued property that is called to convert an object to a primitive value

const x = new LightMap( [ [ 'a', 0 ], [ 'b', 1 ] ] );

'' + x;
// [["a",0],["b",1]]

[ Symbol.toPrimitive( number ) ]:

symbol that specifies a function valued property that is called to convert an object to a primitive value

const x = new LightMap( [ [ 'a', 0 ], [ 'b', 1 ] ] );

+x;
// 2 (size of the Map)