Improvements and additions to Web Serial API docs

files/en-us/web/api/serial/getports/index.md

@@ -29,7 +29,9 @@ A {{jsxref("Promise")}} that resolves with an array of {{domxref("SerialPort")}}
 ### Exceptions
 
 - `SecurityError` {{domxref("DOMException")}}
-  - : The returned `Promise` rejects with this error if a [Permissions Policy](/en-US/docs/Web/HTTP/Permissions_Policy) blocks the use of this feature or a user permission prompt was denied.
+  - : The returned `Promise` rejects with this error in either of the following situations:
+    - A {{httpheader('Permissions-Policy/serial','serial')}} [Permissions Policy](/en-US/docs/Web/HTTP/Permissions_Policy) blocks the use of this feature.
+    - A user permission prompt was denied.
 
 ## Examples
 

files/en-us/web/api/serial/index.md

@@ -17,9 +17,7 @@ The `Serial` interface of the [Web Serial API](/en-US/docs/Web/API/Web_Serial_AP
 
 - {{domxref("Serial.requestPort()")}} {{Experimental_Inline}}
 
-  - : Returns a {{jsxref("Promise")}} that resolves with an instance of {{domxref("SerialPort")}} representing the device chosen by the user or rejects if no device was selected.
-
-    This method must be called with user activation.
+  - : Returns a {{jsxref("Promise")}} that resolves with an instance of {{domxref("SerialPort")}} representing the device chosen by the user. This method must be called via [transient activation](/en-US/docs/Glossary/Transient_activation).
 
 - {{domxref("Serial.getPorts()")}} {{Experimental_Inline}}
   - : Returns a {{jsxref("Promise")}} that resolves with an array of {{domxref("SerialPort")}} objects representing serial ports connected to

files/en-us/web/api/serial/requestport/index.md

@@ -10,7 +10,13 @@ browser-compat: api.Serial.requestPort
 
 {{APIRef("Web Serial API")}}{{SecureContext_Header}}{{SeeCompatTable}}
 
-The **`Serial.requestPort()`** method of the {{domxref("Serial")}} interface returns a {{jsxref("Promise")}} that resolves with an instance of {{domxref("SerialPort")}} representing the device chosen by the user or rejects if no device was selected.
+The **`Serial.requestPort()`** method of the {{domxref("Serial")}} interface presents the user with a dialog asking them to select a serial device to connect to. It returns a {{jsxref("Promise")}} that resolves with an instance of {{domxref("SerialPort")}} representing the device chosen by the user.
+
+## Description
+
+When the user first visits a site it will not have permission to access any serial devices. A site must first call `requestPort()` to prompt the user to select which device the site should be allowed to control.
+
+This method must be called via [transient activation](/en-US/docs/Glossary/Transient_activation). The user has to interact with the page or a UI element in order for this feature to work.
 
 ## Syntax
 
@@ -21,18 +27,20 @@ requestPort(options)
 
 ### Parameters
 
-- `options`
+- `options` {{optional_inline}}
 
   - : An object with the following properties:
 
-    - `filters`
-
-      - : A list of objects containing vendor and product IDs used to search for attached devices. The [USB Implementors Forum](https://www.usb.org/) assigns IDs to specific companies. Each company assigns IDs to its products. Filters contain the following values:
-
-        - `usbVendorId`
-          - : An unsigned short integer that identifies a USB device vendor.
-        - `usbProductId`
-          - : An unsigned short integer that identifies a USB device.
+    - `filters` {{optional_inline}}
+      - : A list of objects containing vendor, product, or Bluetooth service class IDs used to filter the specific device types made available for the user to request a connection to. If no filters are specified, the user is presented with a list of every available device to choose from. Filters can contain the following values:
+        - `bluetoothServiceClassId` {{optional_inline}}
+          - : An unsigned long integer or string representing a Bluetooth service class ID. This can be a 16- or 32-bit UUID alias, any valid UUID, or a valid name from a [GATT assigned services key](https://github.com/WebBluetoothCG/registries/blob/master/gatt_assigned_services.txt).
+        - `usbVendorId` {{optional_inline}}
+          - : An unsigned short integer that identifies a USB device vendor. The [USB Implementors Forum](https://www.usb.org/) assigns IDs to specific vendors.
+        - `usbProductId` {{optional_inline}}
+          - : An unsigned short integer that identifies a USB device. Each vendor assigns IDs to its products.
+    - `allowedBluetoothServiceClassIds` {{optional_inline}}
+      - : A list of unsigned long integers and/or strings representing Bluetooth service class IDs. Bluetooth ports with custom service class IDs are excluded from the list of ports presented to the user unless the service class ID is included in this list. This is true whether you filter the list or not.
 
 ### Return value
 
@@ -41,29 +49,76 @@ A {{jsxref("Promise")}} that resolves with an instance of {{domxref("SerialPort"
 ### Exceptions
 
 - `SecurityError` {{domxref("DOMException")}}
-  - : The returned `Promise` rejects with this error if a [Permissions Policy](/en-US/docs/Web/HTTP/Permissions_Policy) blocks the use of this feature or a user permission prompt was denied.
+  - : The returned `Promise` rejects with this error in either of the following situations:
+    - A {{httpheader('Permissions-Policy/serial','serial')}} [Permissions Policy](/en-US/docs/Web/HTTP/Permissions_Policy) blocks the use of this feature.
+    - A user permission prompt was denied.
 - `NotFoundError` {{domxref("DOMException")}}
-  - : The returned `Promise` rejects with this if the user does not select a port when prompted.
+  - : The returned `Promise` rejects with this exception if the user does not select a port when prompted.
 
-## Security
+## Examples
 
-{{Glossary("Transient activation")}} is required. The user has to interact with the page or a UI element in order for this feature to work.
+### Allow the user to select any device
 
-## Examples
+This example prompts the user to select a device via `requestPort()` when a `<button>` is pressed. It does not include a filter, which means that the selection list will include all available devices:
+
+```html
+<button id="connect">Connect</button>
+```
+
+```js
+const connectBtn = document.getElementById("connect");
+connectBtn.addEventListener("click", () => {
+  try {
+    const port = await navigator.serial.requestPort();
+    // Connect to port or add it to the list of available ports
+  } catch (e) {
+    // The user didn't select a device
+  }
+});
+```
+
+### Allow the user to select a specific vendor's device
 
-The following example shows a filter being passed to `requestPort()` with a USB vendor ID in order to limit the set of devices shown to the user to only USB devices built by a particular manufacturer. If this filter was omitted the user would be able to select any available port.
+In this case, a filter is passed to `requestPort()` with a USB vendor ID to limit the set of devices shown to the user to only USB devices built by a particular manufacturer.
 
 ```js
-button.addEventListener("click", () => {
+connectBtn.addEventListener("click", () => {
   const usbVendorId = 0xabcd;
-  navigator.serial
-    .requestPort({ filters: [{ usbVendorId }] })
-    .then((port) => {
-      // Connect to `port` or add it to the list of available ports.
-    })
-    .catch((e) => {
-      // The user didn't select a port.
-    });
+  try {
+    const port = await navigator.serial.requestPort({ filters: [{ usbVendorId }] });
+    // Connect to port or add it to the list of available ports
+  } catch (e) {
+    // The user didn't select a device
+  }
+});
+```
+
+### Allow the user to select custom RFCOMM-based services
+
+Although most devices expose SPP-based communication through the standardized Bluetooth Classic Serial Port Profile, some use custom RFCOMM-based services. These devices have a Service Class ID that is not in the standard Bluetooth UUID range.
+
+You need to pass the `allowedBluetoothServiceClassIds` list to `requestPort()` to access these custom RFCOMM-based services:
+
+```js
+const myBluetoothServiceUuid = "01234567-89ab-cdef-0123-456789abcdef";
+
+// Prompt user to select any serial port
+// Access to the custom Bluetooth RFCOMM service above will be allowed
+const port = await navigator.serial.requestPort({
+  allowedBluetoothServiceClassIds: [myBluetoothServiceUuid],
+});
+```
+
+You can also use the `bluetoothServiceClassId` filter key when calling `requestPort()` to prompt the user with a list of filtered Bluetooth serial ports identified by Service Class IDs:
+
+```js
+const myBluetoothServiceUuid = "01234567-89ab-cdef-0123-456789abcdef";
+
+// Prompt the user to select Bluetooth serial ports with
+// the custom Bluetooth RFCOMM service above.
+const port = await navigator.serial.requestPort({
+  allowedBluetoothServiceClassIds: [myBluetoothServiceUuid],
+  filters: [{ bluetoothServiceClassId: myBluetoothServiceUuid }],
 });
 ```
 

files/en-us/web/api/serialport/close/index.md

@@ -12,6 +12,56 @@ browser-compat: api.SerialPort.close
 
 The **`SerialPort.close()`** method of the {{domxref("SerialPort")}} interface returns a {{jsxref("Promise")}} that resolves when the port closes.
 
+## Description
+
+`close()` closes the serial port if previously-locked {{domxref("SerialPort.readable")}} and {{domxref("SerialPort.writable")}} members are unlocked, meaning the `releaseLock()` methods have been called for their respective reader and writer.
+
+However, when continuously reading data from a serial device using a loop, the associated [readable stream](/en-US/docs/Web/API/ReadableStream) will always be locked until the [reader](/en-US/docs/Web/API/ReadableStreamDefaultReader) encounters an error. In this case, calling [`reader.cancel()`](/en-US/docs/Web/API/ReadableStreamDefaultReader/cancel) will force [`reader.read()`](/en-US/docs/Web/API/ReadableStreamDefaultReader/read) to resolve immediately with `{ value: undefined, done: true }` allowing the loop to call [`reader.releaseLock()`](/en-US/docs/Web/API/ReadableStreamDefaultReader/releaseLock).
+
+```js
+// Without transform streams.
+
+let keepReading = true;
+let reader;
+
+async function readUntilClosed() {
+  while (port.readable && keepReading) {
+    reader = port.readable.getReader();
+    try {
+      while (true) {
+        const { value, done } = await reader.read();
+        if (done) {
+          // reader.cancel() has been called.
+          break;
+        }
+        // value is a Uint8Array.
+        console.log(value);
+      }
+    } catch (error) {
+      // Handle error...
+    } finally {
+      // Allow the serial port to be closed later.
+      reader.releaseLock();
+    }
+  }
+
+  await port.close();
+}
+
+const closedPromise = readUntilClosed();
+
+document.querySelector("button").addEventListener("click", async () => {
+  // User clicked a button to close the serial port.
+  keepReading = false;
+  // Force reader.read() to resolve immediately and subsequently
+  // call reader.releaseLock() in the loop example above.
+  reader.cancel();
+  await closedPromise;
+});
+```
+
+Closing a serial port is more complicated when using [transform streams](/en-US/docs/Web/API/TransformStream). See [Close a serial port](https://developer.chrome.com/docs/capabilities/serial#close-port) for guidance.
+
 ## Syntax
 
 ```js-nolint

files/en-us/web/api/serialport/forget/index.md

@@ -10,7 +10,13 @@ browser-compat: api.SerialPort.forget
 
 {{securecontext_header}}{{APIRef("Web Serial API")}}{{SeeCompatTable}}{{AvailableInWorkers("window_and_dedicated")}}
 
-The **`SerialPort.forget()`** method of the {{domxref("SerialPort")}} interface returns a {{jsxref("Promise")}} that resolves when the serial port is closed and is forgotten.
+The **`SerialPort.forget()`** method of the {{domxref("SerialPort")}} interface returns a {{jsxref("Promise")}} that resolves when access to the serial port is revoked.
+
+## Description
+
+A website can clean up permissions to access a serial port it is no longer interested in retaining by calling `SerialPort.forget()`. Calling this "forgets" the device, resetting any previously-set permissions so the calling site can no longer communicate with the port.
+
+For example, for an educational web application used on a shared computer with many devices, a large number of accumulated user-generated permissions creates a poor user experience.
 
 ## Syntax
 
@@ -24,7 +30,7 @@ None.
 
 ### Return value
 
-A {{jsxref("Promise")}} that resolves with `undefined` once the connection is closed, the device is forgotten, and the permission is reset.
+A {{jsxref("Promise")}} that resolves with `undefined` once the connection is revoked.
 
 ## Specifications
 

files/en-us/web/api/serialport/getinfo/index.md

@@ -10,7 +10,7 @@ browser-compat: api.SerialPort.getInfo
 
 {{SecureContext_Header}}{{APIRef("Web Serial API")}}{{SeeCompatTable}}{{AvailableInWorkers("window_and_dedicated")}}
 
-The **`getInfo()`** method of the {{domxref("SerialPort")}} interface returns an object whose properties are the vendor ID and product ID of the device.
+The **`getInfo()`** method of the {{domxref("SerialPort")}} interface returns an object containing identifying information for the device available via the port.
 
 ## Syntax
 
@@ -24,12 +24,44 @@ None.
 
 ### Return value
 
-An object containing the following values.
+An object containing the following properties:
 
 - `usbVendorId`
-  - : If the port is part of a USB device, an unsigned short integer that identifies a USB device vendor, otherwise `undefined`.
+  - : If the port is part of a USB device, this property is an unsigned short integer that identifies the device's vendor. If not, it is `undefined`.
 - `usbProductId`
-  - : If the port is part of a USB device, an unsigned short integer that identifies a USB device, otherwise `undefined`.
+  - : If the port is part of a USB device, this property is an unsigned short integer that identifies the USB device. If not, it is `undefined`.
+- `bluetoothServiceClassId`
+  - : If the port is a Bluetooth RFCOMM service, this property is an unsigned long integer or string representing the device's Bluetooth service class ID. If not, it is `undefined`.
+
+## Example
+
+This snippet calls the {{domxref("Serial.requestPort()")}} method when a `<button>` is pressed. We pass a filter to `requestPort()` to filter for Arduino Uno USB devices. Once a port is requested, we call `getInfo()` to return the device's `usbProductId` and `usbVendorId`.
+
+```html
+<button id="connect">Connect</button>
+```
+
+```js
+const connectBtn = document.getElementById("connect");
+
+// Filter for devices with the Arduino Uno USB Vendor/Product IDs
+const filters = [
+  { usbVendorId: 0x2341, usbProductId: 0x0043 },
+  { usbVendorId: 0x2341, usbProductId: 0x0001 }
+];
+
+connectBtn.addEventListener("click", () => {
+  try {
+    // Prompt the user to select an Arduino Uno device
+    const port = await navigator.serial.requestPort({ filters });
+
+    // Return the device's identifying info
+    const { usbProductId, usbVendorId } = port.getInfo();
+  } catch (e) {
+    // The user didn't select a device
+  }
+});
+```
 
 ## Specifications
 

files/en-us/web/api/serialport/index.md

@@ -27,9 +27,9 @@ Instances of this interface may be obtained by calling methods of the {{domxref(
 ## Instance methods
 
 - {{domxref("SerialPort.forget()")}} {{Experimental_Inline}}
-  - : Returns a {{jsxref("Promise")}} that resolves when the port closes and is forgotten.
+  - : Returns a {{jsxref("Promise")}} that resolves when access to the serial port is revoked. Calling this "forgets" the device, resetting any previously-set permissions so the calling site can no longer communicate with the port.
 - {{domxref("SerialPort.getInfo()")}} {{Experimental_Inline}}
-  - : Returns an object containing properties of the port.
+  - : Returns an object containing identifying information for the device available via the port.
 - {{domxref("SerialPort.open()")}} {{Experimental_Inline}}
   - : Returns a {{jsxref("Promise")}} that resolves when the port is opened. By default the port is opened with 8 data bits, 1 stop bit and no parity checking.
 - {{domxref("SerialPort.setSignals()")}} {{Experimental_Inline}}

files/en-us/web/api/web_serial_api/index.md

@@ -31,6 +31,11 @@ Examples of serial devices include 3D printers, and microcontrollers such as the
 - {{domxref("WorkerNavigator.serial")}} {{ReadOnlyInline}} {{Experimental_Inline}}
   - : Returns a {{domxref("Serial")}} object, which represents the entry point into the Web Serial API to enable the control of serial ports.
 
+## HTTP headers
+
+- {{httpheader("Permissions-Policy")}} {{httpheader('Permissions-Policy/serial','serial')}} directive
+  - : Controls whether the current document is allowed to use the Web Serial API to communicate with serial devices, either directly connected via a serial port, or via USB or Bluetooth devices emulating a serial port.
+
 ## Examples
 
 The following examples demonstrate some of the functionality provided by the Web Serial API.