An array is a collection of values, stored contiguously.
📦 Node.js, 🌐 Web, 📜 Files, 📰 Docs, 📘 Wiki.

This package includes comprehensive set of array functions with which you can generate an array, clone it, query about it, get non-negative indices, manage its length, get/set elements, fully or partially sort it, obtain minimum(s)/maximum(s), compare it with another array, get a part of it, search a value, obtain all possible arrangements or random arrangements, find an element, take/drop elements or scan from its beginning or its end, search the index of a part of it, perform functional operations, flatten multi-level arrays, obtain prefix sum, manipulate it in various ways, count/partition elements, split it, concatenate/join multiple arrays, rearrange elements within it, or performing set operations upon it.

We use a consistent naming scheme that helps you quickly identify the functions you need. All functions except from*() take array as 1st parameter. Some functions operate on a specified range in the array and are called ranged*(), such as rangedPartialSort(). Functions like swap() are pure and do not modify the array itself, while functions like swap$() do modify (update) the array itself. Some functions accept a map function for faster comparison, such as unique(). Further, functions which return an iterable instead of an array are prefixed with i, such as isubsequences(). We borrow some names from other programming languages such as Haskell, Python, Java, and Processing.

With this package, you can simplify the implementation of complex algorithms, and be able to achieve your goals faster, regardless of your level of expertise. Try it out today and discover how it can transform your development experience! This package is available in Node.js and Web formats. To use it on the web, simply use the extra_array global variable after loading with a <script> tag from the jsDelivr CDN.

Stability: Experimental.

NOTE: The use of negative indices in certain functions such as slice() is provided as a convenience for access elements from the end of the array. However, negative indices can be thought of as referring to a virtual mirrored version of the original array, which can be counter-intuitive and make it harder to reason about the behavior of functions that use them. We are working on a solution to this problem. Any suggestions are welcome.

const xarray = require('extra-array');
// import * as xarray from "extra-array";
// import * as xarray from "https://unpkg.com/extra-array/index.mjs"; (deno)

var x = [1, 2, 3];
xarray.get(x, -1);
// → 3

var x = [1, 2, 3, 4];
xarray.swap(x, 0, 1);
// → [ 2, 1, 3, 4 ]

var x = [1, 2, 3, 4];
xarray.rotate(x, 1);
// → [ 2, 3, 4, 1 ]

xarray.permutations([1, 2, 3]);
// → [
//   [],          [ 1 ],
//   [ 2 ],       [ 3 ],
//   [ 1, 2 ],    [ 1, 3 ],
//   [ 2, 1 ],    [ 2, 3 ],
//   [ 3, 1 ],    [ 3, 2 ],
//   [ 1, 2, 3 ], [ 1, 3, 2 ],
//   [ 2, 1, 3 ], [ 2, 3, 1 ],
//   [ 3, 1, 2 ], [ 3, 2, 1 ]
// ]

• Prefix sum array and difference array : Woburn C.I. PEGWiki
• How to get the count of each distinct value in a column?
• How to add region in java script file, visual studio
• Operator precedence - JavaScript : MDN Web Docs
• numpy.partition - NumPy Manual