Merge pull request #496 from scalacenter/scalajs-bundler-release

Add a blog post introducing scalajs-bundler

Author: heathermiller

blog/_posts/2016-10-19-scalajs-bundler.md

@@ -0,0 +1,75 @@
+---
+layout: blog
+post-type: blog
+by: Julien Richard-Foy
+title: "Use npm packages in Scala.js with scalajs-bundler"
+---
+
+This week we release the first version of
+[*scalajs-bundler*](https://scalacenter.github.io/scalajs-bundler), a tool that makes it easier
+to use [npm](https://www.npmjs.com/) packages for [Scala.js](https://www.scala-js.org/)
+developers. This effort follows a Scala Center Advisory Board
+[proposal](https://scala.epfl.ch/minutes/2016/06/06/may-9-2016.html#proposal-scp-005-ensurance-of-continuity-of-scalajs-project):
+“ensurance of continuity of the Scala.js project”.
+
+## Vision
+
+Our goal is to make npm dependencies management as easy as JVM dependencies management.
+
+Basically, if your application needs to use an npm package `foo`, all you have to do is to
+add to your build a line like the following:
+
+~~~ scala
+npmDependencies in Compile += "foo" -> "1.0"
+~~~
+
+And then the usual `run` and `test` sbt commands just work.
+
+## Challenge
+
+npm is the most popular JavaScript package registry. How can Scala.js applications benefit from
+the many libraries published on npm? First, this requires to resolve and download these libraries
+including their transitive dependencies. Then, the artifacts
+need to be *linked* with the Scala.js code. This last step is subtler than it seems
+because the linking process varies according to the target execution environment. For instance,
+Node.js expects artifacts to conform to the CommonJS format, whereas this format is not compatible
+with the execution from a web browser. Furthermore, in the case of web development, when the
+application is shipped to production it is better to pack all the code and its dependencies into a
+single bundle whose format is executable by web browsers.
+
+## Existing solutions
+
+There are mainly two existing approaches to tackle these challenges: using
+[WebJars](http://www.webjars.org/) or combining two build systems (one for the Scala
+world and one for the npm world). Both of them require extra efforts from developers
+or have limitations (you can find more details about that in scalajs-bundler’s
+[documentation](https://scalacenter.github.io/scalajs-bundler/motivation.html)).
+
+## Current state
+
+*scalajs-bundler* leverages the
+[CommonJS modules support](https://www.scala-js.org/doc/project/module.html) brought by the latest
+Scala.js release.
+
+The 0.1 release contains an sbt plugin that:
+
+- lets developers define their npm dependencies (as in the introductory example),
+- keeps track of transitive npm dependencies between Scala.js artifacts,
+- fetches these dependencies from the npm registry,
+- provides tasks to bundle the application into a single artifact executable by web browsers.
+
+The plugin uses [npm](https://www.npmjs.com/) and [webpack](https://webpack.github.io/)
+under the hood.
+
+We also provide a second sbt plugin that integrates with
+[sbt-web-scalajs](https://github.com/vmunier/sbt-web-scalajs): it basically turns bundles
+into sbt-web assets.
+
+## Future work
+
+There is still some work to do (in particular to shorten the duration of the bundling process
+in the context of live reloading workflows) and we expect to release a
+[0.2 version](https://github.com/scalacenter/scalajs-bundler/milestone/1) soon, but this
+first release is already usable, so don’t hesitate to
+[give it a try](https://scalacenter.github.io/scalajs-bundler/getting-started.html), we’d love
+to get your feedback!