Handling dependencies with Deno

Github: deno-check-updates

Deno: deno_check_updates

Introduction

Deno first stable version is just out and everyone went crazy about it, as shown in bestofjs Deno is getting an average of 700 stars daily!

That's why I gave it a try to see what's all the hype is about. So far I really like how straightforward and simple it is but one thing I didn't like is how handling the dependencies work.

The easy way

In all docs/tutorials importing any deno dependency (standard or third party) would look something like this:

import { v4 } from "https://deno.land/std/uuid/mod.ts";

The code looks simple we are importing the uuid standard library from the given link but what if you look closely you can understand that deno.land is a 'mirror' for the deno project on Github and that link actually points here mod.ts and that's simply the code source in the master branch.

So the question here what if we want to use a specific version and not always the latest one ?

Easy! you can just change the import to :

import { v4 } from "https://deno.land/std@0.52.0/uuid/mod.ts";

As you can see by adding the @0.52.0 now we are pointing the dependency to the exact version 0.52.0 and this way we will avoid having any breaking changes and we can safely updated the dependencies manually.

The Import Maps

As simple as it is, the first solution introduces a major inconvenient : If I use one dependency in 20 files, each time I updated I need to update them manually one by one!

To solve this problem Deno introduced an unstable feature (for now) which is import maps as mentioned in the documentation you can use import maps with the --importmap=<FILE> CLI flag.

You will have to create an import file and use it like the following:
Example:

// import_map.json

{
   "imports": {
      "http/": "https://deno.land/std@0.52.0/http/"
   }
}

// hello_server.ts

import { serve } from "http/server.ts";

const body = new TextEncoder().encode("Hello World\n");
for await (const req of serve(":8000")) {
  req.respond({ body });
}

$ deno run --allow-net --importmap=import_map.json --unstable hello_server.ts

Deno check updates

Although the import maps is still unstable and have some limitations (refer to documentation) but it makes handling the dependencies fairly easy. One limitation I noticed is that (unlike npm) there is no command to check if the dependencies are up to date or not.

That's why I've been working on deno-check-updates. using the module is easy you just need to run the command:

$ deno run -A --unstable https://deno.land/x/deno_check_updates/main.ts -f import_map.json

The script will parse the import_map.json file and list all the dependencies with the latest versions. Something like this :

{
  "imports": {
    "soxa/": "https://deno.land/x/soxa@v1.0/",
    "soxa2/": "https://deno.land/x/soxa@v0.4/",
    "checksum": "https://deno.land/x/checksum@1.2.0",
  }
}

This way you know which dependencies needs an update!