SerialPort.writable

The writable read-only property of the SerialPort interface returns a WritableStream for sending data to the device connected to the port. Chunks written to this stream must be instances of BufferSource (for example, an ArrayBuffer or ArrayBufferView such as Uint8Array). This property is non-null as long as the port is open and has not encountered a fatal error.

A WritableStream

The following example shows how to write a string to a port. A TextEncoder converts the string to a Uint8Array before transmission.

const encoder = new TextEncoder();
const writer = port.writable.getWriter();
await writer.write(encoder.encode("PING"));
writer.releaseLock();