js-array-ext

JavaScript Array Extension

A small library with array generic operations.

Philosophy under the hood

I think that most of the time what algorithm's programer does is iterate in different ways over one or many list of element and for each iteration applying a process. Some of those iteration are simply join, intersection, etc, in the other occasions could be no so easy to see which is the generic iteration/operation we need.

In this small library I try to do basically four things:

• Add basic Array's iterations.
• Add basic operation over Sorted Arrays with unduplicated values, I call those type of arrays as srtf (Sorted and Filtered).
• Add complex Array's iterations.
• Add complex iterations over srtf Arrays.

All the functions in this library are built base on current JS Array methods (see https://www.w3schools.com/jsref/jsref_obj_array.asp) as much as possible or in function defined in this library.

Installation

npm install js-array-ext

API

• Markdown style documentation: API-MD
• HTML style documentation: API-HTML

Usage

import idtArray from 'js-array-ext';
var srt = [0, 1, 2, 3, 4, 5];
var compareNumber = (num1, num2) => num1 - num2;
var srtSliceFind = idtArray.sliceFind(srt, 3, compareNumber);

Output should be [3, 4, 5]

Comparisons

Before

var xCoords = [3, 4, 6, 8];
var yCoords = [1, 5, 2, 4];
var points = [];
xCoords.forEach(x => yCoords.forEach(y, => points.push({x, y}) ) );

After

import idtArray from 'js-array-ext';
var xCoords = [3, 4, 6, 8];
var yCoords = [1, 5, 2, 4];
// We provide the combine function, we do not need call twice forEach anymore.
var points = idtArray.combine(xCoords, yCoords, (x, y) => ({x, y}));

Bonus

If we want a new list of sorted points base on point distance to origin (0, 0) we can just do:

var DD = p => p.x * p.x + p.y * p.y; // DD is for Delta * Delta.
var PPDistance = (p1, p2) => DD(p1) - DD(p2);
var srtPnts = idtArray.sort(points, PPDistance);

Tests

npm test

Future Functions

splitFilter(array, processFunction)

Split array in tree Array, one for elements in which processFunction return negative number, one for case return cero and one for case return positive numbers.

reduceMap(array, processFunction, reduceFunction, initial)

Call to processFunction for each element and and push each result in an Array. Then call to reduceFunction in same way as Array.reduce. Default for initial is an empty Array and default for reduceFunction is Array.concat

Contributing

So far only my self.