Slim Dependencies

[cpojer]

Also see facebook/create-react-app#1183

We should focus on reducing the amount of dependencies that are shipped with Jest. Is there somebody that could do an analysis?

[wtgtybhertgeghgtwtg]

I thought I was dreaming when I saw this issue.

• node-notifier dropping the CLI will help. It used a very uncommon CLI library. Updates node-notifier dep of jest-cli to v5 #2718 resolved this.
• istanbul-reports moving from handlebars to something else would help. handlebars requires uglifyjs for its CLI, and the handlebars team is not interested in moving the CLI to another package. An issue has been raised, but there has been no response.
• escodgen moving the CLI to another package would remove optionator and its dependencies from the dependency graph. An issue has been raised, but there has been no response.
• jsdom replacing request with something like got would remove request from the dependency tree. It also might speed it up a bit, too. They might look to do it if they can get better coverage, first.
• istanbul-reports packages a .nyc_output folder of ~310 KB. A PR has been filed.
• If an issue with vm-browserify can be resolved (or, better yet, a new version written), jsdom won't need to use escodgen or acorn-globals, so acorn stuff can be removed from the dependency tree.

[cpojer]

ah, it sucks that all of these are transitive dependencies and that we don't really have much control over it.

[kentcdodds]

Can I just say that @wtgtybhertgeghgtwtg's analysis is incredibly thorough. Thank you for doing that

[orta]

Yep, this is really great work - thanks @wtgtybhertgeghgtwtg

[cpojer]

note-notifier dropped the cli: #2718

[JaKXz]

The istanbul-reports PR has been merged and released! 😃

[cpojer]

Nice!

[wtgtybhertgeghgtwtg]

Just an overview of the impact this has had.
jest@19.0.0 is about seven dependencies and one megabyte lighter than jest@18.1.0. Here's a comparison of the node_modules of a fresh install of the two (Windows 10, yarn@0.20.3)

[cpojer]

Nice work, thanks @wtgtybhertgeghgtwtg for working on this and getting back with more data :)

[mhart]

It was lighter until request v2.80.0 went ahead and destroyed all the gains:

http://pkgsize.com/jest.html (select an area to zoom in and hover to see the event that caused the change)

which is largely:

http://pkgsize.com/jest-cli.html

The big ones there are:

• http://pkgsize.com/jest-environment-jsdom.html due to http://pkgsize.com/jsdom.html due mostly to http://pkgsize.com/request.html

• http://pkgsize.com/istanbul-api.html due to

  • http://pkgsize.com/istanbul-lib-instrument.html due to http://pkgsize.com/babel-generator.html due to http://pkgsize.com/babel-runtime.html due to the ever increasing http://pkgsize.com/core-js.html
  • http://pkgsize.com/istanbul-reports.html due to http://pkgsize.com/handlebars.html due largely to http://pkgsize.com/uglify-js.html (kind of unfortunate that the handlebars package includes both the runtime and CLI)

• http://pkgsize.com/jest-runtime.html due mostly to http://pkgsize.com/babel-core.html and http://pkgsize.com/jest-config.html (though sharing/de-duping of the latter two with jest-environment-jsdom decreases jest-runtime's impact on jest-cli) and http://pkgsize.com/yargs.html

[sanyatuning]

+1

[cpojer]

I think we are mostly good on this for now and we sped Jest's startup up by more than 50% with Jest 21. If anybody wants to drop more stuff, please feel free to comment here and send PRs!