AngularJS - 使用ng-class指令在特定按钮上切换类

Directive

myApp.directive('vlcObject', function ($compile, $rootScope, $timeout, $window) {
var vlcPlayerId = '';
var linker = function (scope, element, attrs) {

scope.muteClass = 'fa fa-volume-on';

<button id=mute_uniqId ng-click="doMute(uniqId)"><i ng-class="muteClass"></i></button>

scope.doMute = function(uniqId){
    var vlc = scope.getVLC("vlc");
     if (vlc && vlc.playlist.isPlaying) {
        vlc.audio.toggleMute();
        scope.controlClass = 'fa fa-volume-off';
    }else{
        scope.controlClass = 'fa fa-volume-on';
    }
}

};
return {
    restrict: "E",
    link: linker
};
myApp.directive('vlcObject', functi