How to use the onvif.Cam function in onvif

// TODO checken of er altijd een this.credentials bestaat, indien username en paswoord niet ingevuld is.
            
            // The client credentials will only contain the data (i.e. user name or password) which has changed.
            // The other data is not changed, so we will need use the original data stored on the server.
            clientConfig.username = clientConfig.user || this.credentials.user;
            clientConfig.password = clientConfig.password || this.credentials.password;
                    
            // When the user appends some new text to the existing password, then the original password is passed via the client as __PWRD__
            // So replace __PWRD__ again by the original password.
            if (clientConfig.password && this.credentials.password) {
               clientConfig.password.replace('___PWRD__', this.credentials.password);
            }
     
            if (this.credentials.user !== clientConfig.user || this.credentials.password !== clientConfig.password || this.xaddress !== clientConfig.hostname){
                var cam = new onvif.Cam(clientConfig, function(err) {             
                    if (!err) {
                        if (cam.profiles) {
                            for(var i = 0; i < cam.profiles.length; i++) {
                                profileNames.push({
                                    label: cam.profiles[i].name,
                                    value: cam.profiles[i].$.token
                                });
                            }
                        }
                        
                        response.json(profileNames);
                    }
                });
            }
            else {
                if (this.cam.profiles) {

return;
        }
        
        setOnvifStatus(node, "initializing");
        
        var options = {};
        options.hostname = this.xaddress;
        options.port = this.port;
        
        if (this.credentials && this.credentials.user) {
            options.username = this.credentials.user;
            options.password = this.credentials.password;
        }

        // Create a new camera instance, which will automatically connect to the device (to load configuration data)
        this.cam = new onvif.Cam(options, function(err) { 
            if (err) {
                // Make sure the Catch-node can catch the error
                node.error( err, {} );
                
                setOnvifStatus(node, "disconnected");
            }
            else {  
                setOnvifStatus(node, "connected"); 
            }
        });
        
        node.on('close', function(){
			setOnvifStatus(node, "");
            
            node.removeAllListeners("onvif_status");
		});