feat: initial polyfill functionality

package.json

@@ -3,7 +3,17 @@
   "version": "0.4.3",
   "description": "libdatachannel node bindings",
   "type": "module",
-  "exports": "./lib/index.js",
+  "exports": {
+    ".": {
+      "import": "./lib/index.js"
+    },
+    "./polyfill": {
+      "import": "./polyfill/polyfill.js"
+    },
+    "./ponyfill": {
+      "import": "./polyfill/ponyfill.js"
+    }
+  },
   "typings": "lib/index.d.ts",
   "engines": {
     "node": ">=12.0.0"
@@ -70,9 +80,11 @@
     "typescript": "^4.6.3"
   },
   "dependencies": {
-    "prebuild-install": "^7.1.1"
+    "p-defer": "^4.0.0",
+    "prebuild-install": "^7.1.1",
+    "uint8-util": "^2.2.2"
   },
   "bundleDependencies": [
     "prebuild-install"
   ]
-}
+}

polyfill/Events.js

@@ -0,0 +1,27 @@
+// @ts-check
+
+export class PeerConnectionIceEvent extends Event {
+    #candidate = null;
+    get candidate() {
+        return this.#candidate;
+    }
+
+    constructor(candidate) {
+        super('icecandidate');
+
+        this.#candidate = candidate;
+    }
+}
+
+export class DataChannelEvent extends Event {
+    #channel = null;
+    get channel() {
+        return this.#channel;
+    }
+
+    constructor(channel) {
+        super('datachannel');
+
+        this.#channel = channel;
+    }
+}

polyfill/RTCDataChannel.js

@@ -1,14 +1,75 @@
-import DOMException from 'node-domexception';
+// @ts-check
+import { text2arr } from 'uint8-util';
 // DOMException has existed for quite a while, but was only exposed in node 17 and above, this is a hack to get it early in engines 10 or above tho we only support since node 15 for event target
 
 // eslint-disable-next-line @typescript-eslint/no-empty-function
 const noop = () => {};
-
-export default class RTCDataChannel extends EventTarget {
-    constructor() {
+/**
+ * @class
+ * @implements {RTCDataChannel}
+ */
+export default class extends EventTarget {
+    /**
+     * @param {import("../lib/index.d.ts").DataChannel} dataChannel
+     * @param {any} opts
+     */
+    constructor(dataChannel, opts = {}) {
         super();
+
+        this.#dataChannel = dataChannel;
+        this.#readyState = 'connecting';
+        this.#bufferedAmountLowThreshold = 0;
+
+        this.#binaryType = 'arraybuffer';
+
+        this.#dataChannel.onOpen(() => {
+            this.#readyState = 'open';
+            this.dispatchEvent(new Event('open'));
+        });
+        this.#dataChannel.onClosed(() => {
+            this.#readyState = 'closed';
+            this.dispatchEvent(new Event('close'));
+        });
+        this.#dataChannel.onError((/** @type {string | undefined} */ msg) => {
+            this.#readyState = 'closed';
+            this.dispatchEvent(
+                new RTCErrorEvent('error', {
+                    error: new RTCError(
+                        {
+                            errorDetail: 'data-channel-failure',
+                        },
+                        msg,
+                    ),
+                }),
+            );
+        });
+        this.#dataChannel.onBufferedAmountLow(() => {
+            this.dispatchEvent(new Event('bufferedamountlow'));
+        });
+        this.#dataChannel.onMessage((/** @type {string | Uint8Array} */ data) => {
+            if (typeof data === 'string') {
+                data = text2arr(data);
+            }
+
+            this.dispatchEvent(new MessageEvent('message', { data }));
+        });
+
+        // forward events to properties
+        this.addEventListener('message', this.onmessage);
+        this.addEventListener('bufferedamountlow', this.onbufferedamountlow);
+        this.addEventListener('error', this.onerror);
+        this.addEventListener('close', this.onclose);
+        this.addEventListener('closing', this.onclosing);
+        this.addEventListener('open', this.onopen);
+
+        this.#maxPacketLifeTime = opts.maxPacketLifeTime ?? null;
+        this.#maxRetransmits = opts.maxRetransmits ?? null;
+        this.#negotiated = opts.negotiated ?? false;
+        this.#ordered = opts.ordered ?? true;
     }
 
+    #dataChannel;
+    /** @type {BinaryType} */
     #binaryType = 'blob';
 
     set binaryType(type) {
@@ -24,10 +85,8 @@ export default class RTCDataChannel extends EventTarget {
         return this.#binaryType;
     }
 
-    #bufferedAmount = 0;
-
     get bufferedAmount() {
-        return this.#bufferedAmount;
+        return this.#dataChannel.bufferedAmount();
     }
 
     #bufferedAmountLowThreshold = 0;
@@ -39,18 +98,15 @@ export default class RTCDataChannel extends EventTarget {
     set bufferedAmountLowThreshold(value) {
         const number = Number(value) || 0;
         this.#bufferedAmountLowThreshold = number;
+        this.#dataChannel.setBufferedAmountLowThreshold(number);
     }
 
-    #id = 0;
-
     get id() {
-        return this.#id;
+        return this.#dataChannel.getId();
     }
 
-    #label = 0;
-
     get label() {
-        return this.#label;
+        return this.#dataChannel.getLabel();
     }
 
     #maxPacketLifeTime = 0;
@@ -65,7 +121,7 @@ export default class RTCDataChannel extends EventTarget {
         return this.#maxRetransmits;
     }
 
-    #negotiated = 0;
+    #negotiated = false;
 
     get negotiated() {
         return this.#negotiated;
@@ -79,20 +135,19 @@ export default class RTCDataChannel extends EventTarget {
     onmessage = noop;
     onopen = noop;
 
-    #ordered = 0;
+    #ordered = false;
 
     get ordered() {
         return this.#ordered;
     }
 
-    #protocol = 0;
-
     get protocol() {
-        return this.#protocol;
+        return this.#dataChannel.getProtocol();
     }
 
     // connecting, open, closing, or closed
-    #readyState = 0;
+    /** @type {RTCDataChannelState} */
+    #readyState = 'connecting';
 
     get readyState() {
         return this.#readyState;
@@ -105,7 +160,23 @@ export default class RTCDataChannel extends EventTarget {
                 'InvalidStateError',
             );
         }
-        // Needs network error, type error implemented and strict data type checking.
-        // This may be a string, a Blob, an ArrayBuffer, a TypedArray or a DataView object.
+
+        // Needs network error, type error implemented
+        if (typeof data === 'string') {
+            this.#dataChannel.sendMessage(data);
+        } else if (data instanceof Blob) {
+            data.arrayBuffer().then((ab) => {
+                this.#dataChannel.sendMessageBinary(new Uint8Array(ab));
+            });
+        } else {
+            this.#dataChannel.sendMessageBinary(new Uint8Array(data));
+        }
+    }
+
+    close() {
+        this.#readyState = 'closing';
+        this.dispatchEvent(new Event('closing'));
+
+        this.#dataChannel.close();
     }
 }