LittleJS VS colyseus

Checkout LittleJS, MelonJS and my main recommendation, Phaser.

I myself am currently using LittleJS, and it's just amazing for me, as it sorts out the core engine & rendering logic, but I can easily reuse and plug in any sort of other libraries/old scripts from other games at need: https://github.com/KilledByAPixel/LittleJS

Check out LittleJS: https://github.com/KilledByAPixel/LittleJS

exhibit B: Little JS, my open source game engine written from scratch

View on GitHub

If you don't want to dive deep into backend then https://colyseus.io/ might also be an option.

Since you already know Javascript you could try to use some existing server framework at first to avoid having to do everything from scratch. https://github.com/colyseus/colyseus

Try this Node.js based server framework https://github.com/colyseus/colyseus

https://colyseus.io/ (Authoritative server, that works with many engines JavaScript/Phaser/Unity/Haxe/Defold)

Also check Colyseus. Bit similar multiplayer server framework and built on top of Node.js/TypeScript. https://github.com/colyseus/colyseus

The above project uses a Node.js authoritative game state called Colyseus (https://github.com/colyseus/colyseus) which handles the state synchronisation between clients and server.

We use Colyseus for this. Pretty easy and open source too. https://colyseus.io/

https://colyseus.io/ (Authoritative server, that works with many engines JavaScript/Phaser/Unity/Haxe/Defold)

On a lower level, I have been using Colyseus (https://github.com/colyseus/colyseus) which is, in the words of the author: "[...] an Authoritative Multiplayer Framework for Node.js, with clients available for the Web, Unity3d, Defold, Haxe, and Cocos2d-X.". I have been using it on multiple projects as a state synchronisation library for my browser-based games. It takes cares of all the data synching aspecta among all players in a "room". The community is very active and you will get a lot of help to begin with and scale your creations.

Of course, a lot will have to be done by you for anything like client-side prediction, server reconciliation, lag compensation, entity interpolation, but knowing that the state manages itself is already a huge relief if you are unfamiliar with these concepts.

Another project which already includes many of these features is https://github.com/timetocode/nengi. It is more opinionated and well focused on fast-paced games.

On my side, I have been creating an open-source multiplayer game for the browser that includes client-side prediction, entity interpolation and server reconciliation https://github.com/halftheopposite/tosios.