parcel-plugin-closure

Closure compiler based packager for Parcel

Prerequisites

• Java's JDK 8 (not the JRE), and the JAVA_HOME environment variable defined
• google-closure-compiler and parcel-bundler installed locally

closure-compiler-js is not supported because it does not support modules (used for Parcel code-splitting).

Usage

You just need to add parcel-plugin-closure to your devDependencies :

yarn add parcel-plugin-closure --dev

or

npm install parcel-plugin-closure --save-dev

Configuration

You can pass an optional configuration in a .parcelclosurerc file in the root of your project.

{
	// a list of externs files to pass to Closure
	"externs": ["src/my-externs"],
	"bundles": {
		// You can configure a bundle by referencing it's entry point
		"src/dynamically-imported-file": {
			// the closure optimization level, "simple" or "advanced" defaults to advanced
			"optimization": "advanced",
			// The list of the values exported, this is only needed for dynamically
			// imported modules
			"exports": ["AnExportedValue"]
		}
	}
}

Angular support

The plugin supports lazy-loading with loadChildren, you'll need to specify your factories exports. It already includes the basic externs needed if Angular is detected.

{
	"bundles": {
		"src/shared/components/lazy.module.ngfactory": {
			"exports": ["LazyModuleNgFactory"]
		}
	}
}

Development

This plugin is divided in two part :

• A simple Closure wrapper running in a Java virtual-machine, we need it mainly for the virtual file-system (we give it files as processed by Parcel, not from from the disk)
• The Parcel plugin, it contains a Parcel packager and a JavaScript asset. It calls the Closure wrapper using node-java.

Java part (Kotlin)

You need the Java JDK 8 and Gradle 2.4+ installed.

• Download the Gradle wrapper : gradle wrapper --gradle-version 4.4.1
• Build the jar in build/kotlin/libs : ./gradlew build

JavaScript part (TypeScript)

You need Node.js 8+ and Yarn installed. You can use npm instead of yarn but it will make your setup non-reproductible.

• Fetch the dependencies: yarn or npm install
• Build the JavaScript files in build/javascript : yarn build:ts or npm run build:ts