refactor serial connection to base class and web serial class

src/connection/web_serial_connection.js

@@ -0,0 +1,106 @@
+import SerialConnection from "./serial_connection.js";
+
+class WebSerialConnection extends SerialConnection {
+
+    constructor(serialPort) {
+
+        super();
+
+        this.serialPort = serialPort;
+        this.reader = serialPort.readable.getReader();
+        this.writable = serialPort.writable;
+        this.readLoop();
+
+        // listen for disconnect
+        this.serialPort.addEventListener("disconnect", () => {
+            this.onDisconnected();
+        });
+
+        // fire connected callback after constructor has returned
+        setTimeout(() => {
+            this.onConnected();
+        }, 0);
+
+    }
+
+    static async open() {
+
+        // ensure browser supports web serial
+        if(!navigator.serial){
+            alert("Web Serial is not supported in this browser");
+            return null;
+        }
+
+        // ask user to select device
+        const serialPort = await navigator.serial.requestPort({
+            filters: [],
+        });
+
+        // open port
+        await serialPort.open({
+            baudRate: 115200,
+        });
+
+        return new WebSerialConnection(serialPort);
+
+    }
+
+    async close() {
+
+        // release reader lock
+        try {
+            this.reader.releaseLock();
+        } catch(e) {
+            // console.log("failed to release lock on serial port readable, ignoring...", e);
+        }
+
+        // close serial port
+        try {
+            await this.serialPort.close();
+        } catch(e) {
+            // console.log("failed to close serial port, ignoring...", e);
+        }
+
+    }
+
+    // override
+    async write(bytes) {
+        const writer = this.writable.getWriter();
+        try {
+            await writer.write(new Uint8Array(bytes));
+        } finally {
+            writer.releaseLock();
+        }
+    }
+
+    async readLoop() {
+        try {
+            while(true){
+
+                // read bytes until reader indicates it's done
+                const { value, done } = await this.reader.read();
+                if(done){
+                    break;
+                }
+
+                // pass to super class handler
+                await this.onDataReceived(value);
+
+            }
+        } catch(error) {
+
+            // ignore error if reader was released
+            if(error instanceof TypeError){
+                return;
+            }
+
+            console.error('Error reading from serial port: ', error);
+
+        } finally {
+            this.reader.releaseLock();
+        }
+    }
+
+}
+
+export default WebSerialConnection;