compatible with html-webpack-plugin v4 hooks

index.js

@@ -21,6 +21,8 @@ require('object.values').shim();
 
 const objectAssign = require('object-assign');
 
+const HtmlWebpackPlugin = require('html-webpack-plugin');
+
 const PLUGIN_NAME = 'preload-webpack-plugin';
 
 const weblog = require('webpack-log');
@@ -97,13 +99,15 @@ class PreloadPlugin {
 
   // handler use for webpack v4
   hooksHandler(compilation) {
-    if (!compilation.hooks.htmlWebpackPluginAfterHtmlProcessing) {
+    const beforeEmit = compilation.hooks.htmlWebpackPluginAfterHtmlProcessing ||
+      HtmlWebpackPlugin.getHooks(compilation).beforeEmit;
+    if (!beforeEmit) {
       const message = `compilation.hooks.htmlWebpackPluginAfterHtmlProcessing is lost.
       Please make sure you have installed html-webpack-plugin and put it before ${PLUGIN_NAME}`;
       log.error(message);
       throw new Error(message);
     }
-    compilation.hooks.htmlWebpackPluginAfterHtmlProcessing
+    beforeEmit
       .tapAsync(PLUGIN_NAME, (htmlPluginData, cb) => this.afterHtmlProcessingFn(htmlPluginData, cb, compilation));
   }
 

package.json

@@ -1,11 +1,12 @@
 {
   "name": "preload-webpack-plugin",
-  "version": "2.3.0",
+  "version": "2.3.1",
   "description": "Enhances html-webpack-plugin with link rel=preload wiring capabilities for scripts",
   "main": "index.js",
   "scripts": {
     "lint": "eslint --quiet -f codeframe index.js test/spec.js",
     "lint-fix": "eslint --fix --quiet -f codeframe index.js test/spec.js",
+    "prewebpack-v3-t": "cd test/webpack-v3 && npm install",
     "webpack-v3-t": "node_modules/jasmine/bin/jasmine.js test/webpack-v3.spec.js",
     "test": "node_modules/jasmine/bin/jasmine.js test/spec.js && npm run webpack-v3-t"
   },
@@ -42,7 +43,8 @@
     "webpack": "^4.1.0"
   },
   "peerDependencies": {
-    "webpack": "^4.0.1"
+    "webpack": "^4.0.1",
+    "html-webpack-plugin": "^3.0.6"
   },
   "dependencies": {
     "object-assign": "^4.1.1",