polymer-build is a library for building Polymer projects.
npm install --save-dev polymer-build
The Polymer CLI uses polymer-build under the hood, so you can think of the CLI's
build command like running a pre-configured polymer-build pipeline. Setting this up for you makes the CLI easy to use, but as a command-line wrapper its customization options are more limited. polymer-build allows you to completely customize your build and combine additional streams and build tasks in any order.
Consider using polymer-build instead of the CLI if you:
While polymer-build was built to work easily with Gulp, it can be used in any Node.js environment. polymer-build is built on Node.js streams, and the build pipeline that you create with it is not much more than a series of connected streams. Files are represented as Vinyl file objects, which means that polymer-build can interop with any existing Gulp/Vinyl streams.
Check out the custom-build generator for an example of how polymer-build can be used to build a project.
PolymerProject represents your project in the build pipeline. Once configured, it will give you access to a collection of streams and helpers for building your project.
To create a new instance of
PolymerProject, you'll need to give it some information about your application. If you already have a
polymer.json configuration file in your project, you can create a new
PolymerProject instance by loading it directly:
const PolymerProject = PolymerProject;const project = ;
Or, you can pass in configuration options directly to the
const PolymerProject = PolymerProject;const project =entrypoint: 'index.html'shell: 'src/my-app.html'fragments:'src/my-view1.html''src/my-view2.html''src/my-view3.html';
Returns a readable stream of your project's source files. By default, these are the files in your project's
src/ directory, but if you have additional source files this can be configured via the
sources property in
Returns a readable stream of your project's dependencies. This stream is automatically populated based on the files loaded inside of your project. You can include additional dependencies via the
extraDependencies property in
ProjectOptions (this can be useful when the analyzer fails to detect a necessary dependency.)
const gulp = ;const mergeStream = ;// Create a build pipeline to pipe both streams together to the 'build/' dir;
const gulpif = ;const uglify = ;const cssSlam = gulp;const htmlMinifier = ;const HtmlSplitter = HtmlSplitter;const sourcesHtmlSplitter = ;const sourcesStream = project// split inline JS & CSS out into individual .js & .css files; // rejoins those files back into their original location// NOTE: If you want to split/rejoin your dependencies stream as well, you'll need to create a new HtmlSplitter for that stream.
You can add splitters to any part of your build stream. We recommend using them to optimize your
dependencies() streams individually as in the example above, but you can also optimize after merging the two together or even after bundling.
A stream that combines the files in your application to reduce the number of frontend requests needed. This can be a great way to improve performance when HTTP2/Push is not available.
By default, the bundler will create one "shared-bundle.html" containing all shared dependencies. You can optimize even further by defining "fragments" in your project options. Fragments are lazy loaded parts of the application, typically views and other elements loaded on-demand. When fragments are defined, the bundler is able to create smaller bundles containing code that is only required for specific fragments.
const gulp = ;const mergeStream = ;// Create a build pipeline to bundle our application before writing to the 'build/' dir;
generateServiceWorker() will generate the service worker code based on your build. Unlike other parts of polymer-build,
generateServiceWorker() returns a promise and not a stream. It can only be run after your build has finished writing to disk, so that it is able to analyze the entire build as it exists.
For bundled builds, be sure to set the bundled option to
true. See AddServiceWorkerOptions for a list of all supported options.
const generateServiceWorker = generateServiceWorker;
generateServiceWorker() is built on top of the sw-precache library. Any options it supports can be passed directly to that library via the
swPrecacheConfig option. See sw-preache for a list of all supported options
In some cases you may need to whitelist 3rd party services with sw-precache, so the Service Worker doesn't intercept them. For instance, if you're hosting your app on Firebase, you'll want to add the
navigateFallbackWhitelist: [/^(?!\/__)/] option to your
swPrecacheConfig as Firebase owns the
__ namespace, and intercepting it will cause things like OAuth to fail.
generateServiceWorker(), but writes the generated service worker to the file path you specify in the
path option ("service-worker.js" by default).
const addServiceWorker = addServiceWorker;
Sometimes you'll want to pipe a build to multiple destinations.
forkStream() creates a new stream that copies the original stream, cloning all files that pass through it.
const gulp = ;const mergeStream = ;const forkStream = forkStream;// Create a combined build stream of your application filesconst buildStream = ;// Fork your build stream to write directly to the 'build/unbundled' dirconst unbundledBuildStream =;// Fork your build stream to bundle your application and write to the 'build/bundled' dirconst bundledBuildStream =;
git checkout -b my-new-feature
git commit -am 'Add some feature'
git push origin my-new-feature
You can compile polymer-build from source by cloning the repo and then running
npm run build. Make sure you have already run
npm install before compiling.
polymer-build officially supports the latest LTS (4.x) and stable (6.x) versions of Node.js.