webpack v4 compatibility upgrade

README.md

@@ -4,7 +4,7 @@ A fork of Critical Webpack Plugin.
 
 This is simplified and runs after all files have been emitted so you can use it after Extract Text and HTML Webpack Plugin.
 
-**Note**: [As **critical** itself has a dependency on puppeteer](https://github.com/addyosmani/critical/releases/tag/v1.0.0) in order to run Headless Chrome, consumers of this plugin will need to make sure that their build environment (local, CI, etc) where running webpack with this plugin has the necessary operating system packages installed.  See this page for more information on [troubleshooting](https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md) puppeteer.
+**Note**: [As **critical** itself has a dependency on puppeteer](https://github.com/addyosmani/critical/releases/tag/v1.0.0) in order to run Headless Chrome, consumers of this plugin will need to make sure that their build environment (local, CI, etc) where they are running webpack with this plugin has the necessary operating system packages installed.  See this page for more information on [troubleshooting](https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md) puppeteer.
 
 ### Install
 
@@ -44,6 +44,8 @@ module.export = {
 Read [Critical CSS and Webpack: Automatically Minimize Render-Blocking CSS](https://vuejsdevelopers.com/2017/07/24/critical-css-webpack/) blogpost.
 
 ### Development
+
+#### Local Environment
 Since the main dependency of this project, critical, depends on an environment that supports Headless Chrome, [Docker](https://www.docker.com/) has been provided to support local development of this project.
 
 After you have [installed Docker](https://www.docker.com/community-edition), you can do the following to get setup:
@@ -57,4 +59,9 @@ Now you can run the project's `npm` scripts like usuual:
 
 **_Note_**: changes are bi-directional
 
-Learn more about Docker [here](https://docs.docker.com/get-started/) or [configuring Headless Chrome for your own machine](https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md).
+Learn more about Docker [here](https://docs.docker.com/get-started/) or [configuring Headless Chrome for your own machine](https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md).
+
+#### Workflows
+1. To run unit tests - `npm run test`
+1. To build the project - `npm run ci`
+1. To build the project for release - `npm run build`

index.js

@@ -12,7 +12,7 @@ HtmlCriticalWebpackPlugin.prototype.emit = function(compilation, callback) {
 
 HtmlCriticalWebpackPlugin.prototype.apply = function(compiler) {
   var self = this;
-  compiler.plugin('after-emit', function (compilation, callback) {
+  compiler.hooks.afterEmit.tapAsync('HtmlCriticalWebpackPlugin', function (compilation, callback) {
     self.emit(compilation, callback);
   });
 };