How to detect if microphone permissions have been granted in chrome

Question

I would liked to detect whether or not microphone permissions have been granted on my site when it loads without actually running something like the following:

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Answer 1

Update

microphone has been added to the Permission API even if it's not yet available on Safari nor Internet Explorer.

You could hope that it would be accessible from the permission api, but it isn't :(

Perhaps in the feature this could work like the rest of this:

navigator.permissions.query(
    // { name: 'camera' }
    { name: 'microphone' }
    // { name: 'geolocation' }
    // { name: 'notifications' } 
    // { name: 'midi', sysex: false }
    // { name: 'midi', sysex: true }
    // { name: 'push', userVisibleOnly: true }
    // { name: 'push' } // without userVisibleOnly isn't supported in chrome M45, yet
).then(function(permissionStatus){

    console.log(permissionStatus.state); // granted, denied, prompt

    permissionStatus.onchange = function(){
        console.log("Permission changed to " + this.state);
    }

})

Old answer

The only way i see it possible is if you keep track of this yourself with a key/value item in localStorage when you ask for permission.

Unfortunately it doesn't notify you when it has been changed

// initialization
if( localStorage.getItem('voice_access') === null ){
    // just assume it is prompt
    localStorage.setItem('voice_access', 'prompt');
}

// Then somewhere
navigator.getUserMedia({ audio: true }, function (e) {
    // http://stackoverflow.com/q/15993581/1008999
    //
    // In chrome, If your app is running from SSL (https://),
    // this permission will be persistent.
    // That is, users won't have to grant/deny access every time.
    localStorage.setItem("voice_access", "granted");

}, function (err) {
    if (err.name === 'PermissionDismissedError') {
        localStorage.setItem('voice_access', 'prompt')
    }
    if (err.name === 'PermissionDeniedError') {
        localStorage.setItem('voice_access', 'denied')
    }
})

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You could go the extra mile and build a nice little wrapper with this code above and extend/replace the permission api to handle more enum names and create a broadcast api to tell the other tabs when it changes. but why make it so complicated...? The localStorage can't be 100% trusted. it can be changed anywhere any time both with permission and storage cleared