worker.js

let detector;
onmessage = async (event) => {
	//Depending on the mode
	switch(event.data.cmd)
	{
		case "detector" :
		{
			//get detector
			detector = event.data.port;
			//Listen
			detector.onmessage = (event) => {
				//get face data
				face = event.data;
			};
			//Done
			break;
		}
		case "insert":
		{
			//Get streams
			const {readableStream, writableStream} = event.data;
			//New transform stream for inserting metadata
			const transformStream = new TransformStream ({transform: insert});
			//Pipe
			readableStream
				.pipeThrough (transformStream)
				.pipeTo (writableStream);
			//Done
			break;
		}
		case "extract":
		{
			//Get streams
			const {readableStream, writableStream} = event.data;
			//New transform stream for inserting metadata
			const transformStream = new TransformStream ({transform: extract});
			//Pipe
			readableStream
				.pipeThrough (transformStream)
				.pipeTo (writableStream);
			//Done
			break;
		}
	}
};