feat: optimize JS assets added later by plugins (#373)

src/index.js

@@ -202,11 +202,17 @@ class TerserPlugin {
         .filter((name) => {
           const { info } = compilation.getAsset(name);
 
-          // Skip double minimize assets from child compilation
-          if (info.minimized) {
+          if (
+            // Skip double minimize assets from child compilation
+            info.minimized ||
+            // Skip minimizing for extracted comments assets
+            info.extractedComments
+          ) {
             return false;
           }
 
+          console.log(info);
+
           if (
             !compiler.webpack.ModuleFilenameHelpers.matchObject.bind(
               // eslint-disable-next-line no-undefined
@@ -552,7 +558,9 @@ class TerserPlugin {
             };
           }
 
-          compilation.emitAsset(commentsFilename, extractedCommentsSource);
+          compilation.emitAsset(commentsFilename, extractedCommentsSource, {
+            extractedComments: true,
+          });
 
           return {
             commentsFilename,
@@ -626,6 +634,7 @@ class TerserPlugin {
           name: pluginName,
           stage:
             compiler.webpack.Compilation.PROCESS_ASSETS_STAGE_OPTIMIZE_SIZE,
+          additionalAssets: true,
         },
         (assets) =>
           this.optimize(compiler, compilation, assets, {

test/TerserPlugin.test.js

@@ -14,6 +14,7 @@ import {
   ModifyExistingAsset,
   compile,
   countPlugins,
+  EmitNewAsset,
   getCompiler,
   getErrors,
   getWarnings,
@@ -1608,4 +1609,19 @@ describe("TerserPlugin", () => {
     expect(getErrors(stats)).toMatchSnapshot("errors");
     expect(getWarnings(stats)).toMatchSnapshot("warnings");
   });
+
+  it("should run plugin against assets added later by plugins", async () => {
+    const compiler = getCompiler({
+      entry: path.resolve(__dirname, "./fixtures/entry.js"),
+    });
+
+    new TerserPlugin().apply(compiler);
+    new EmitNewAsset({ name: "newFile.js" }).apply(compiler);
+
+    const stats = await compile(compiler);
+
+    expect(readsAssets(compiler, stats)).toMatchSnapshot("assets");
+    expect(getErrors(stats)).toMatchSnapshot("errors");
+    expect(getWarnings(stats)).toMatchSnapshot("warnings");
+  });
 });

test/__snapshots__/TerserPlugin.test.js.snap

@@ -88,6 +88,17 @@ exports[`TerserPlugin should respect the hash options #1: errors 1`] = `Array []
 
 exports[`TerserPlugin should respect the hash options #1: warnings 1`] = `Array []`;
 
+exports[`TerserPlugin should run plugin against assets added later by plugins: assets 1`] = `
+Object {
+  "main.js": "(()=>{var r={791:r=>{r.exports=function(){console.log(7)}}},o={};!function t(e){if(o[e])return o[e].exports;var n=o[e]={exports:{}};return r[e](n,n.exports,t),n.exports}(791)})();",
+  "newFile.js": "var foo=\\"bar\\",bar=\\"foo\\";",
+}
+`;
+
+exports[`TerserPlugin should run plugin against assets added later by plugins: errors 1`] = `Array []`;
+
+exports[`TerserPlugin should run plugin against assets added later by plugins: warnings 1`] = `Array []`;
+
 exports[`TerserPlugin should work (without options): assets 1`] = `
 Object {
   "main.js": "(()=>{var r={791:r=>{r.exports=function(){console.log(7)}}},o={};!function t(e){if(o[e])return o[e].exports;var n=o[e]={exports:{}};return r[e](n,n.exports,t),n.exports}(791)})();",

test/helpers/EmitNewAsset.js

@@ -0,0 +1,31 @@
+export default class EmitNewAsset {
+  constructor(options = {}) {
+    this.options = options;
+  }
+
+  apply(compiler) {
+    const pluginName = this.constructor.name;
+
+    const { RawSource } = compiler.webpack.sources;
+
+    compiler.hooks.compilation.tap(pluginName, (compilation) => {
+      compilation.hooks.processAssets.tap(
+        {
+          name: pluginName,
+          stage: compiler.webpack.Compilation.PROCESS_ASSETS_STAGE_REPORT,
+        },
+        () => {
+          // eslint-disable-next-line no-param-reassign
+          compilation.emitAsset(
+            this.options.name,
+            new RawSource(`
+var foo =    'bar';
+
+var bar    = 'foo';
+            `)
+          );
+        }
+      );
+    });
+  }
+}

test/helpers/index.js

@@ -1,6 +1,7 @@
 import BrokenCodePlugin from "./BrokenCodePlugin";
 import compile from "./compile";
 import countPlugins from "./countPlugins";
+import EmitNewAsset from "./EmitNewAsset";
 import execute from "./execute";
 import ExistingCommentsFile from "./ExistingCommentsFile";
 import getCompiler from "./getCompiler";
@@ -15,6 +16,7 @@ export {
   BrokenCodePlugin,
   compile,
   countPlugins,
+  EmitNewAsset,
   ExistingCommentsFile,
   execute,
   getCompiler,