Static Builds with Rollup Optimization

To build our component for use in other projects, we can use the SystemJS static build to create an optimized component file to share.

This is handled via jspm build in jspm which takes similar arguments to jspm bundle, but instead of storing a registry entry for each module, it will try to fully optimize the inter-module dependencies.

Whenever there are sub-trees of ES modules within the build tree, SystemJS Builder will inline any of these trees together using Rollup. This allows unused exports to be removed via code tree analysis. If the whole module tree consists only of ES modules, then the entire tree can be inlined with Rollup, giving the best possible code optimization.

In case it is not already obvious, Rollup is amazing.

Let's create a dist folder then output a built component into this folder:

jspm build jspm-react-component/component.js dist/jspm-react-component.js \
  --externals react
  --format umd --global-name jspmReactComponent --global-deps "{'react':'React'}" --skip-source-maps

To break down the options we've provided:

  • On the first line, we indicate we want to build the module jspm-react-component/component.js into the output build file dist/jspm-react-component.js.
  • --externals react indicates that React should be excluded from the build as a dependency.
  • --format umd outputs a built file that will work as AMD, CommonJS or a global.
  • --global-name jspmReactComponent means that when running as a global, it will create global.jspmReactComponent as the value of jspm-react-component
  • --global-deps "{'react':'React'}" indicates that our dependency on react should refer to the global React when running as a global.
  • --skip-source-maps since we don't need references to the original sources anymore we can skip source map generation.

Neither --global-name nor --global-deps would have been necessary if running a CJS, AMD or ESM format build.

We should then see the following output in the console:

     Creating the single-file build for jspm-react-component/component.js...

       ┌─ jspm-react-component/component.js
       ├─ npm:[email protected]/babel-helpers/classCallCheck.js
       ├─ npm:[email protected]/babel-helpers/possibleConstructorReturn.js
       ├─ npm:[email protected]/babel-helpers/createClass.js
       └─ npm:[email protected]/babel-helpers/inherits.js

ok   Fully-optimized - entire tree built via Rollup static optimization.

ok   Built into dist/jspm-react-component.js, unminified as umd.

Fully-optimized indicates that the entire tree has been built with Rollup, including inlining the Babel transform helpers.

The full output of this file can be seen at

By default builds, like bundles, build for the browser in production. We can pass the --node or --dev options to both the build and bundle commands to build the Node and development conditional paths respectively. These conditional loading techniques are covered in the last two sections.