Rollup

.gitignore

@@ -1,2 +1,3 @@
 *.log
 node_modules
+dist

babel.config.js

@@ -0,0 +1,20 @@
+let presets = [
+    ["@babel/preset-env", {
+        targets: {
+            "electron": 5
+        }
+    }]
+];
+
+let plugins = [];
+
+if (process.env.BABEL_ENV === "development") {
+    plugins.push("@babel/plugin-transform-modules-commonjs")
+}
+
+module.exports = {
+    presets: presets,
+    plugins: plugins,
+    exclude: "node_modules/**",
+    sourceMaps: "inline"
+}

lib/html-preview.js

@@ -1,6 +1,4 @@
-'use babel'
-
-import { ScrollView } from 'atom-space-pen-views'
+import ScrollView from 'atom-space-pen-views-plus/src/scroll-view'
 import fs from 'fs-plus'
 import path from 'path'
 
@@ -81,3 +79,9 @@ export default class HTMLPreview extends ScrollView {
         return this.detach()
     }
 }
+
+export function deserialize({filePath, uri}) {
+    if (fs.isFileSync(filePath)) {
+        return new HTMLPreview(uri)
+    }
+}

lib/main.js

@@ -1,17 +1,24 @@
-'use babel'
 import { CompositeDisposable } from 'atom'
 import path from 'path'
 
 let subs = null
 let toolbar = null
 let juliaClient = null
-let HTMLPreviewView = require('./html-preview.js')
+
+// ./html-preview.js exports
+let HTMLPreviewView = null
+let deserializeHTML = null
 
 export function activate () {
     subs = new CompositeDisposable()
 
     subs.add(atom.workspace.addOpener((uri) => {
         if (path.extname(uri) === '.html' && uri.startsWith('preview://')) {
+
+            // load HTMLPreviewView if null
+            if (HTMLPreviewView == null) {
+                import('./html-preview').then(({default: HTMLPreview}) => HTMLPreviewView = HTMLPreview)
+            }
             return new HTMLPreviewView(uri)
         }
     }))
@@ -145,7 +152,9 @@ export function deactivate () {
 }
 
 export function deserialize({filePath, uri}) {
-    if (require('fs-plus').isFileSync(filePath)) {
-        return new HTMLPreviewView(uri)
+    // load deserializeHTML if null
+    if (deserializeHTML == null) {
+        import('./html-preview').then(({deserialize}) => deserializeHTML = deserialize)
     }
+    return deserializeHTML({filePath, uri})
 }