add SSE support #12

CHANGELOG.md

@@ -1,3 +1,11 @@
+## 0.3.0
+### Features
+* add `sse()` method for Server-Sent Events [#12](https://github.com/jcubic/wayne/issues/12)
+
+## 0.2.1
+### Bugs
+* fix cross-origin redirect [#2](https://github.com/jcubic/wayne/issues/2)
+
 ## 0.2.0
 ### Features
 * allow to use without ES Module [#9](https://github.com/jcubic/wayne/issues/9)

README.md

@@ -3,7 +3,7 @@
        alt="Logo of Wayne library - it represent constrution worker helmet and text with the name of the library" />
 </h1>
 
-[![npm](https://img.shields.io/badge/npm-0.2.1-blue.svg)](https://www.npmjs.com/package/@jcubic/wayne)
+[![npm](https://img.shields.io/badge/npm-0.3.0-blue.svg)](https://www.npmjs.com/package/@jcubic/wayne)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://makeapullrequest.com)
 
 [Service Worker Routing library for in browser HTTP requests](https://github.com/jcubic/wayne/)
@@ -210,6 +210,7 @@ Code contributions are also welcome.
 ## Aknowledge
 * Part of the content of this README was based on text from [MDN](https://developer.mozilla.org/).
 * Logo use illustration from [OpenClipart](https://openclipart.org/detail/320906/hard-hat).
+* This article was helpful [SSEGWSW: Server-Sent Events Gateway by Service Workers](https://medium.com/its-tinkoff/ssegwsw-server-sent-events-gateway-by-service-workers-6212c1c55184)
 
 ## License
 

index.js

@@ -48,6 +48,40 @@ export class HTTPResponse {
     }
     this._resolve(Response.redirect(url, code));
   }
+  sse({ onClose } = {}) {
+    let send, close, stream, defunct;
+    stream = new ReadableStream({
+      cancel() {
+        defunct = true;
+        trigger(onClose);
+      },
+      start: controller => {
+        send = function(event) {
+          if (!defunct) {
+            const chunk = createChunk(event);
+            const payload = new TextEncoder().encode(chunk);
+            controller.enqueue(payload);
+          }
+        };
+        close = function close() {
+          controller.close();
+          stream = null;
+          trigger(onClose);
+        };
+      }
+    });
+    this._resolve(new Response(stream, {
+      headers: {
+        'Content-Type': 'text/event-stream; charset=utf-8',
+        'Transfer-Encoding': 'chunked',
+        'Connection': 'keep-alive'
+      }
+    }));
+    return {
+      send,
+      close
+    };
+  }
 }
 
 // code extracted from https://github.com/jcubic/route.js
@@ -149,6 +183,19 @@ function error404(path) {
   }];
 }
 
+function createChunk({ data, event, retry, id }) {
+  return Object.entries({ event, id, data, retry })
+    .filter(([, value]) => value)
+    .map(([key, value]) => `${key}: ${value}`)
+    .join('\n') + '\n\n';
+}
+
+function trigger(maybeFn, ...args) {
+  if (typeof maybeFn === 'function') {
+    maybeFn(...args);
+  }
+}
+
 export class Wayne {
   constructor() {
     this._routes = {};

index.umd.js

@@ -75,6 +75,47 @@ class HTTPResponse {
     this._resolve(Response.redirect(url, code));
   }
 
+  sse({
+    onClose
+  } = {}) {
+    let send, close, stream, defunct;
+    stream = new ReadableStream({
+      cancel() {
+        defunct = true;
+        trigger(onClose);
+      },
+
+      start: controller => {
+        send = function (event) {
+          if (!defunct) {
+            const chunk = createChunk(event);
+            const payload = new TextEncoder().encode(chunk);
+            controller.enqueue(payload);
+          }
+        };
+
+        close = function close() {
+          controller.close();
+          stream = null;
+          trigger(onClose);
+        };
+      }
+    });
+
+    this._resolve(new Response(stream, {
+      headers: {
+        'Content-Type': 'text/event-stream; charset=utf-8',
+        'Transfer-Encoding': 'chunked',
+        'Connection': 'keep-alive'
+      }
+    }));
+
+    return {
+      send,
+      close
+    };
+  }
+
 } // code extracted from https://github.com/jcubic/route.js
 // Copyright (C) 2014-2017 Jakub T. Jankiewicz <https://jcubic.pl/me>
 
@@ -170,6 +211,26 @@ function error404(path) {
   }];
 }
 
+function createChunk({
+  data,
+  event,
+  retry,
+  id
+}) {
+  return Object.entries({
+    event,
+    id,
+    data,
+    retry
+  }).filter(([, value]) => value).map(([key, value]) => `${key}: ${value}`).join('\n') + '\n\n';
+}
+
+function trigger(maybeFn, ...args) {
+  if (typeof maybeFn === 'function') {
+    maybeFn(...args);
+  }
+}
+
 class Wayne {
   constructor() {
     this._routes = {};