es6->es5

-const usePwa = location.protocol === 'https:';
+const isHttps = location.protocol === 'https:';
+const usePwa = isHttps;
 
 window.addEventListener('load', function() {
     if ('serviceWorker' in navigator) {
@@ -14,15 +15,17 @@ window.addEventListener('load', function() {
                 console.log('SW registration failed: ', err);
             });
         } else {
-            navigator.serviceWorker.getRegistrations().then(function(registrations) {
-                for (let registration of registrations) {
-                    registration.unregister().then(result => {
-                        console.log('SW unregisted: ', result);
-                    }).catch(err => {
-                        console.log('SW unregistration failed: ', err);
-                    });
-                }
-            });
+            if (isHttps) {
+                navigator.serviceWorker.getRegistrations().then(function(registrations) {
+                    for (let registration of registrations) {
+                        registration.unregister().then(result => {
+                            console.log('SW unregisted: ', result);
+                        }).catch(err => {
+                            console.log('SW unregistration failed: ', err);
+                        });
+                    }
+                });
+            }
         }
     }
 });

@@ -84,7 +84,7 @@ self.addEventListener('install', function(event) {
     // );
 });
 
-self.addEventListener('error', event => {
+self.addEventListener('error', function(event) {
     console.error('error', event);
 
     // 上报错误信息
@@ -96,7 +96,7 @@ self.addEventListener('error', event => {
     // event.error.stack
 });
 
-self.addEventListener('unhandledrejection', event => {
+self.addEventListener('unhandledrejection', function(event) {
     console.error('unhandledrejection', event);
 
     // 上报错误信息