Allow selectively including polyfills (#30)

Co-authored-by: Richie Bendall <[email protected]>

Author: rjerue

index.d.ts

@@ -1,3 +1,4 @@
+import { MergeExclusive } from "type-fest"
 import { Compiler } from "webpack"
 
 declare namespace NodePolyfillPlugin {
@@ -34,12 +35,21 @@ declare namespace NodePolyfillPlugin {
         | "vm"
         | "zlib"
 
-	export interface Options {
+	interface IncludeOptions {
 		/**
-		By default, the modules that were polyfilled in Webpack 4 are mirrored over. However, if you don't want a module like console to be polyfilled you can specify alises to be skipped here.
-		*/
+                By default, the modules that were polyfilled in Webpack 4 are mirrored over. However, you can choose to only include certain aliases. For example, you can only have `console` polyfilled.
+                */
+		includeAliases?: readonly Alias[]
+	}
+
+	interface ExcludeOptions {
+		/**
+                By default, the modules that were polyfilled in Webpack 4 are mirrored over. However, if you don't want a module like `console` to be polyfilled you can specify alises to be skipped here.
+                */
 		excludeAliases?: readonly Alias[]
 	}
+
+	export type Options = MergeExclusive<IncludeOptions, ExcludeOptions>
 }
 
 declare class NodePolyfillPlugin {

index.js

@@ -2,25 +2,38 @@
 const { ProvidePlugin } = require("webpack")
 const filterObject = require("filter-obj")
 
-const excludeObjectKeys = (object, excludeKeys) => filterObject(object, key => !excludeKeys.includes(key))
+function createAliasFilter({ includeAliases, excludeAliases }) {
+	if (includeAliases.length > 0) {
+		return object => filterObject(object, key => includeAliases.includes(key))
+	}
+
+	return object => filterObject(object, key => !excludeAliases.includes(key))
+}
 
 module.exports = class NodePolyfillPlugin {
 	constructor(options = {}) {
 		this.options = {
 			excludeAliases: [],
+			includeAliases: [],
 			...options
 		}
+
+		if (this.options.includeAliases.length > 0 && this.options.excludeAliases.length > 0) {
+			throw new Error("excludeAliases and includeAliases are mutually exclusive")
+		}
 	}
 
 	apply(compiler) {
-		compiler.options.plugins.push(new ProvidePlugin(excludeObjectKeys({
+		const filter = createAliasFilter(this.options)
+
+		compiler.options.plugins.push(new ProvidePlugin(filter({
 			Buffer: [require.resolve("buffer/"), "Buffer"],
 			console: require.resolve("console-browserify"),
 			process: require.resolve("process/browser")
-		}, this.options.excludeAliases)))
+		})))
 
 		compiler.options.resolve.fallback = {
-			...excludeObjectKeys({
+			...filter({
 				assert: require.resolve("assert/"),
 				buffer: require.resolve("buffer/"),
 				console: require.resolve("console-browserify"),
@@ -51,7 +64,7 @@ module.exports = class NodePolyfillPlugin {
 				util: require.resolve("util/"),
 				vm: require.resolve("vm-browserify"),
 				zlib: require.resolve("browserify-zlib")
-			}, this.options.excludeAliases),
+			}),
 			...compiler.options.resolve.fallback
 		}
 	}

package.json

@@ -45,6 +45,7 @@
 		"string_decoder": "^1.3.0",
 		"timers-browserify": "^2.0.12",
 		"tty-browserify": "^0.0.1",
+		"type-fest": "^2.13.1",
 		"url": "^0.11.0",
 		"util": "^0.12.4",
 		"vm-browserify": "^1.1.2"

readme.md

@@ -35,6 +35,8 @@ module.exports = {
 
 Type: `object`
 
+`excludeAliases` and `includeAliases` are mutually exclusive.
+
 #### excludeAliases
 
 By default, the modules that were polyfilled in Webpack 4 are mirrored over. However, if you don't want a module like `console` to be polyfilled you can specify alises to be skipped here.
@@ -52,6 +54,23 @@ module.exports = {
 }
 ```
 
+#### includeAliases
+
+Alternatively, you can choose to only include certain aliases. For example, you can only have `console` polyfilled.
+
+```js
+const NodePolyfillPlugin = require("node-polyfill-webpack-plugin")
+
+module.exports = {
+	// Other rules...
+	plugins: [
+		new NodePolyfillPlugin({
+			includeAliases: ["console"]
+		})
+	]
+}
+```
+
 ## Aliases
 
 ### Globals

test.js

@@ -3,7 +3,7 @@ const test = require("ava")
 const webpack = require("p-webpack")
 const NodePolyfillPlugin = require(".")
 
-test("main", async t => {
+test.serial("main", async t => {
 	await webpack({
 		entry: "./fixture",
 		output: {
@@ -22,4 +22,38 @@ test("main", async t => {
 
 	// https://github.com/browserify/console-browserify/blob/f7eefc7c908c29d2e94954e5c6c1098e8c1028b4/index.js#L63
 	t.false(fs.readFileSync("./dist/main.js").toString().includes("No such label: "))
+
+	// https://github.com/feross/buffer/blob/master/index.js#L80
+	t.true(fs.readFileSync("./dist/main.js").toString().includes("is invalid for option \"size\""))
+})
+
+test.serial("includeAliases", async t => {
+	await webpack({
+		entry: "./fixture",
+		output: {
+			library: {
+				type: "commonjs-module"
+			}
+		},
+		plugins: [
+			new NodePolyfillPlugin({
+				includeAliases: ["console"]
+			})
+		]
+	})
+
+	t.is(require("./dist/main.js"), "Hello World")
+
+	// https://github.com/browserify/console-browserify/blob/f7eefc7c908c29d2e94954e5c6c1098e8c1028b4/index.js#L63
+	t.true(fs.readFileSync("./dist/main.js").toString().includes("No such label: "))
+
+	// https://github.com/feross/buffer/blob/master/index.js#L80
+	t.false(fs.readFileSync("./dist/main.js").toString().includes("is invalid for option \"size\""))
+})
+
+test("includeAliases and excludeAliases used at the same time", t => {
+	t.throws(() => new NodePolyfillPlugin({
+		includeAliases: ["console"],
+		excludeAliases: ["crypto"]
+	}), { instanceOf: Error })
 })