site.js

/*
    Requests the navigator.mediaDevices for video input.
*/
export async function requestVideoDevices() {
    try {
        // Ask the first time to prime the underlying device list.
        let devices = await navigator.mediaDevices.enumerateDevices();
        if (devices &&
            (devices.length === 0 || devices.every(d => d.deviceId === ""))) {
            await navigator.mediaDevices.getUserMedia({
                video: true
            });
        }

        // Ask again, if the user allowed it the device list is now poplated.
        // If not, the const returns an empty array.
        devices = await navigator.mediaDevices.enumerateDevices();
        if (devices && devices.length) {
            const deviceResults = [];
            devices.filter(device => device.kind === 'videoinput')
                .forEach(device => {
                    const { deviceId, label } = device;
                    deviceResults.push({ deviceId, label });
                });

            return JSON.stringify(deviceResults);
        }
    } catch (error) {
        console.log(error);
    }

    return JSON.stringify([]);
}