Tap into compiler's emit hook

lib/plugin.js

@@ -1,53 +1,30 @@
 "use strict";
 
-const RawSource = require("webpack-sources").RawSource;
-
 const log = require("./logger").log;
-const RuleSet = require("./rule-set");
-const CompiledChunks = require("./compiled-chunks");
-const publicPath = require("./public-path");
-const TemplatedAssets = require("./templated-assets");
+const tap = require("./tap");
 
 class Plugin {
   constructor(opts) {
-    const options = opts || {};
+    let options = opts || {};
     if (!options.rules) {
       log("No rules specified. No templated chunks will be outputted.");
       log(options);
+      options.rules = [];
     }
-
-    this.rules = RuleSet.from(options.rules);
+    this.pluginName = "TemplatedAssetsWebpackPlugin";
+    this.pluginOptions = options;
   }
 
   apply(compiler) {
-    compiler.plugin("emit", (compilation, callback) => {
-      const chunks = new CompiledChunks(
-        compilation.chunks,
-        compilation.assets,
-        publicPath(compilation)
-      ).chunks;
-
-      new TemplatedAssets(chunks, this.rules)
-        .process()
-        .then(templatedAssets => {
-          templatedAssets.forEach(asset => {
-            if (!asset.emitAsset) return;
-            try {
-              compilation.assets[asset.filename] = new RawSource(asset.source);
-            } catch (e) {
-              throw new Error(
-                `Failed to include asset ${JSON.stringify(
-                  asset
-                )} to compilation.
-${e.message}`
-              );
-            }
-          });
-
-          callback();
-        })
-        .catch(log);
-    });
+    if (!!compiler.hooks) {
+      compiler.hooks.emit.tapAsync(this.pluginName, (compilation, callback) =>
+        tap(this.pluginOptions, compilation, callback)
+      );
+    } else {
+      compiler.plugin("emit", (compilation, callback) =>
+        tap(this.pluginOptions, compilation, callback)
+      );
+    }
   }
 }
 

lib/tap.js

@@ -0,0 +1,37 @@
+const RawSource = require("webpack-sources").RawSource;
+
+const RuleSet = require("./rule-set");
+const CompiledChunks = require("./compiled-chunks");
+const publicPath = require("./public-path");
+const TemplatedAssets = require("./templated-assets");
+const log = require("./logger").log;
+
+function tap(options, compilation, callback) {
+  const rules = RuleSet.from(options.rules);
+  const chunks = new CompiledChunks(
+    compilation.chunks,
+    compilation.assets,
+    publicPath(compilation)
+  ).chunks;
+
+  new TemplatedAssets(chunks, rules)
+    .process()
+    .then(templatedAssets => {
+      templatedAssets.forEach(asset => {
+        if (!asset.emitAsset) return;
+        try {
+          compilation.assets[asset.filename] = new RawSource(asset.source);
+        } catch (e) {
+          throw new Error(
+            `Failed to include asset ${JSON.stringify(asset)} to compilation.
+${e.message}`
+          );
+        }
+      });
+
+      callback();
+    })
+    .catch(log);
+}
+
+module.exports = tap;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "templated-assets-webpack-plugin",
-  "version": "1.2.0",
+  "version": "1.3.0",
   "description": "webpack plugin for creating assets to be used with server rendered web frameworks.",
   "main": "index.js",
   "dependencies": {

test/plugin-init-test.js

@@ -2,18 +2,15 @@ import test from "ava";
 import Plugin from "../lib/plugin";
 
 test("fallback to empty rule set", t => {
-  const ruleSet = new Plugin().rules;
-  const rules = ruleSet.rules;
-
+  const { rules } = new Plugin().pluginOptions;
   t.true(Array.isArray(rules));
   t.is(rules.length, 0);
 });
 
 test("init rules", t => {
-  const ruleSet = new Plugin({
+  const { rules } = new Plugin({
     rules: [{ name: "an-entry" }]
-  }).rules;
-  const rules = ruleSet.rules;
+  }).pluginOptions;
 
   t.true(Array.isArray(rules));
   t.is(rules.length, 1);