wait on async fuction + - asynchronous

Question

I want to get the last deviceId.
Please try the following code on a smartphone.
https://www.ofima.ch/file1.html
Inside the function "getConnectedDevices" the variable deviceId ok.
But outside is returned a promise and not the variable deviceId.
How can I get the variable deviceId ?
Thanks
Miche

Answer 1

Explanation:
You need to wrap your alert in an async function and use await. Also to take the value from the promise you needed .then(). Hope the below helps.
Original code:
async function getConnectedDevices() {
var index;
const devices = await navigator.mediaDevices.enumerateDevices();
for (var i=0; i<devices.length; i++) {
if (devices[i].kind == "videoinput") {
index = i;
}
}
var deviceId = devices[index].deviceId;
alert('deviceId is ok: ' + deviceId);
return (deviceId);
}
const deviceId = getConnectedDevices();
alert('deviceId is not defined, why ?: ' + deviceId);
New code:
async function getConnectedDevices() {
let index;
const devices = await navigator.mediaDevices.enumerateDevices();
for (let i=0; i < devices.length; i++) {
console.debug(devices[i]);
if (devices[i].kind == "videoinput") {
index = i;
}
}
console.log('deviceId is ok: ', devices[index]);
return devices[index].deviceId;
}
(async() => {
const deviceId = await getConnectedDevices().then();
alert(`deviceId: ${deviceId}`);
})();
And a quick hack for storing the deviceId in the window
console.log('globalDeviceId should be undefined', window.globalDeviceObj);
async function getConnectedDevices() {
let index;
const devices = await navigator.mediaDevices.enumerateDevices();
for (let i = 0; i < devices.length; i++) {
console.debug(devices[i]);
if (devices[i].kind == "videoinput") {
index = i;
}
}
console.log('deviceId is ok', devices[index]);
return devices[index];
}
function getDeviceId() {
(async() => {
window.globalDeviceObj = await getConnectedDevices().then();
console.log(`globalDeviceId set: ${JSON.stringify(window.globalDeviceObj)}`);
})();
}
function tick() {
if(typeof window.globalDeviceObj === 'undefined'){
requestAnimationFrame(tick);
}else {
alert(`globalDeviceId get: ${JSON.stringify(window.globalDeviceObj)}, with deviceId: ${(window.globalDeviceObj.deviceId)}`)
}
}
function init() {
tick();
getDeviceId();
}
init();