fix: Add some code splitting for PWA build (#937)

* fix: Add some code splitting for PWA build

* Fix missing files

extensions/dicom-html/.webpack/webpack.prod.js

@@ -1,3 +1,4 @@
+const webpack = require('webpack');
 const merge = require('webpack-merge');
 const path = require('path');
 const webpackCommon = require('./../../../.webpack/webpack.commonjs.js');
@@ -34,5 +35,10 @@ module.exports = (env, argv) => {
       libraryExport: 'default',
       filename: pkg.main,
     },
+    plugins: [
+      new webpack.optimize.LimitChunkCountPlugin({
+        maxChunks: 1,
+      }),
+    ],
   });
 };

extensions/dicom-html/src/asyncComponent.js

@@ -0,0 +1,37 @@
+/**
+ * We use this component to leverage "Code Splitting"
+ *
+ * Link: https://serverless-stack.com/chapters/code-splitting-in-create-react-app.html
+ */
+
+import React, { Component } from 'react';
+
+export default function asyncComponent(importComponent) {
+  class AsyncComponent extends Component {
+    constructor(props) {
+      super(props);
+
+      this.state = {
+        component: null,
+      };
+    }
+
+    async componentDidMount() {
+      // Add dynamically loaded component to state
+      const { default: component } = await importComponent();
+
+      this.setState({
+        component: component,
+      });
+    }
+
+    render() {
+      const C = this.state.component;
+
+      // Render the loaded component, or null
+      return C ? <C {...this.props} /> : null;
+    }
+  }
+
+  return AsyncComponent;
+}

extensions/dicom-html/src/index.js

@@ -1,5 +1,11 @@
+import asyncComponent from './asyncComponent.js';
 import OHIFDicomHtmlSopClassHandler from './OHIFDicomHtmlSopClassHandler.js';
-import OHIFDicomHtmlViewport from './OHIFDicomHtmlViewport.js';
+
+const OHIFDicomHtmlViewport = asyncComponent(() =>
+  import(
+    /* webpackChunkName: "OHIFDicomHtmlViewport" */ './OHIFDicomHtmlViewport.js'
+  )
+);
 
 export default {
   /**
@@ -12,5 +18,5 @@ export default {
   },
   getSopClassHandlerModule() {
     return OHIFDicomHtmlSopClassHandler;
-  }
+  },
 };