Hi! This is my first DEV post. Recently I had to use some sets in my Javascript code that needed to contain objects as items. The problem is the browser `Set` object compares their items by equality. So I decide to create a micro-library in which you can use sets that can handle all the set operation comaprinf the items with an id as a key. Let me introduce you to the library [SmartSet](https://www.npmjs.com/package/smart-set) # Installation If you want to use my library you can install it easily by npm or yarn. ```shell npm install smart-set yarn add smart-set ``` # Creation and operations The `SmartSet` class extends the `Set` class, so every member of `Set` is available, and compatible with the `Set` interface. ## Constructor `SmartSet` has two template paramters: - `T` is the type of items - `ID` is the type of the key (must be primitive) `SmartSet` constructor requires a function that determines the id of an item which should be unique and primitive. The second parameter is a list of items of `T`, which will be the starting data of the set. These items will be unique in the set. ```typescript import { SmartSet } from "smart-set"; interface Data { id: string }; const mySet = new SmartSet(item => item.id, [{ id: 'id1' }, { id: 'id2' }, { id: 'id1' }]); ``` ## Addition The `add(item: T)` and `addAll(items: T[])` functions add item(s) to the set uniquely by the given id function. ```typescript mySet.add({ id: 'id3' }); mySet.add({ id: 'id1' }); mySet.addAll([{ id: 'id1' }, { id: 'id4' }, { id: 'id5' }]); ``` ## Deletion The `delete(item: T)` and `deleteId(id: ID)` functions delete an item by the given id function. The `clear()` function deletes all elements. ```typescript mySet.delete({ id: 'id3' }); mySet.deleteId('id1'); mySet.clear(); ``` ## Containment The `has(item: T): boolean` and `hasId(id: ID): boolean` check whether an item is part of the set by the given id function. ```typescript mySet.has({ id: 'id3' }) === false; mySet.hasId('id1') === true; ``` ## Iteration `SmartSet` is iterable and has the `keys(): IterableIterator`, `values(): IterableIterator` and `entries(): IterableIterator<[ID, T]>` functions for iterating the set. Keys are the values of the `ID` type. ```typescript const mySet = new SmartSet(item => item.id, [{ id: 'id1' }, { id: 'id2' }, { id: 'id3' }]); [...mySet.keys()] === ['id1', 'id2', 'id3']; [...mySet.values()] === [{ id: 'id1' }, { id: 'id2' }, { id: 'id3' }]; [...mySet.entries()] === [['id1', { id: 'id1' }], ['id2', { id: 'id2' }], ['id3', { id: 'id3' }]]; [...mySet] === [{ id: 'id1' }, { id: 'id2' }, { id: 'id3' }]; mySet.forEach((value, key, set) => { /* something with the key, value and set */ }) ``` ## Set operations `SmartSet` has some set operation that corresponds to the mathematics representation. These operations are immutable, so they return a new `SmartSet` instance and does not modify the original set. The methods accept regular `Set` objects, because it runs the ID creation function on the items. `union(other: Set): SmartSet` `intersection(other: Set): SmartSet` `difference(other: Set): SmartSet` `symmetricDifference(other: Set): SmartSet` ```typescript let result; const setA = new SmartSet(item => item.s, [ { s: '1' }, { s: '2' } ]); const setB = new SmartSet(item => item.s, [ { s: '1' }, { s: '3' } ]); result = setA.union(setB); // [ { s: '1' }, { s: '2' }, { s: '3' } ] result = setA.intersection(setB); // [ { s: '1' } ] result = setA.difference(setB); // [ { s: '2' } ] result = setB.difference(setA); // [ { s: '3' } ] result = setA.symmetricDifference(setB); // [ { s: '2' }, { s: '3' } ] ``` # Closing words As I am new to library publishing and open source world it would be a huge help if you could take a look at my source code or report an issue at the repository of the package at [github](https://github.com/dbalazs97/smart-set). Thanks for reading my first post.

dbalazs97

My first npm package is about sets

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