Fix contenthash placeholder for Webpack 4.3+

Closes #78

examples/webpack4-contenthash/README.md

@@ -0,0 +1,3 @@
+# Ensure contenthash path variable works in Webpack 4.3+
+
+Test case for issue #78

examples/webpack4-contenthash/chunk.js

@@ -0,0 +1 @@
+console.log('ok');

examples/webpack4-contenthash/index.js

@@ -0,0 +1,3 @@
+require.ensure([], require => {
+  require('./chunk.js');
+});

examples/webpack4-contenthash/test.js

@@ -0,0 +1,12 @@
+var webpackVersionComponents = require('webpack/package.json').version.split(
+  '.'
+);
+var webpackVersionMajor = Number(webpackVersionComponents[0]);
+var webpackVersionMinor = Number(webpackVersionComponents[0]);
+
+module.exports.skip = function skip() {
+  return (
+    webpackVersionMajor < 4 ||
+    (webpackVersionMajor === 4 && webpackVersionMinor < 3)
+  );
+};

examples/webpack4-contenthash/webpack.config.js

@@ -0,0 +1,18 @@
+var SriPlugin = require("webpack-subresource-integrity");
+var HtmlWebpackPlugin = require("html-webpack-plugin");
+
+module.exports = {
+  entry: "./index.js",
+  mode: "production",
+  output: {
+    filename: "[name].[contenthash].js",
+    chunkFilename: "[name].[contenthash].js",
+    crossOriginLoading: "anonymous"
+  },
+  plugins: [
+    new HtmlWebpackPlugin(),
+    new SriPlugin({
+      hashFuncNames: ["sha256", "sha384"]
+    })
+  ]
+};

util.js

@@ -118,11 +118,13 @@ function getChunkFilename(compilation, chunk) {
   var args = [isInitialChunk(chunk) ? filename : chunkFilename, {
     hash: compilation.hash.substr(0, compilation.mainTemplate.outputOptions.hashDigestLength),
     hashWithLength: length => compilation.hash.substr(0, length),
+    contentHashType: "javascript",
     chunk: {
       id: chunk.id,
       hash: chunk.hash.substr(0, compilation.mainTemplate.outputOptions.hashDigestLength),
       hashWithLength: length => chunk.hash.substr(0, length),
-      name: chunk.name
+      name: chunk.name,
+      contentHash: chunk.contentHash
     }
   }];