How do I call an object within a function in javascript?

Question

Here's my code:

function getIPAddress(url) {
    var v4 = '[\\d]{1-3}';
    var v4d = '\\.';
    var v4complete = v4+v4d+v4+v4d+v4+v4d+v4
    var v6 = '[\\da-fA-F]{0-4}';
    var v6d = ':';
    var v6complete = v6+v6d+v6+v6d+v6+v6d+v6+v6d+v6+v6d+v6+v6d+v6+v6d+v6;
    var regex = new RegExp('(' + v4complete + '(\\:\d+){0,1}|'
                            + '::|::1|'
                            + '\\[::\\]:\\d+|\\[::1\\]|'
                            + v6complete + '|'
                            + '\\[' + v6complete + '\\]' + ')', 'g');
    return url.match(regex);
}

var HOSTNAME = getIPAddress(localStorage.getItem('ipaddress')),
PORT = 80,
USERNAME = localStorage.getItem('ipusername'),
PASSWORD = localStorage.getItem('ippassword'),
STOP_DELAY_MS = 50;

var Cam = require('./lib/onvif').Cam;
var keypress = require('keypress');

var camera = new Cam({
    hostname : HOSTNAME,
    username : USERNAME,
    password : PASSWORD,
    port : PORT,
    timeout : 10000
}, this.CamFunc = function (err) {
    if (err) {
        console.log(err);
        return;
    }

    var cam_obj = this;
    var preset_names = [];
    var preset_tokens = [];

    cam_obj.getStreamUri({
        protocol : 'RTSP'
    },  // Completion callback function
        // This callback is executed once we have a StreamUri
        function (err, stream, xml) {
            if (err) {
                console.log(err);
                return;
            } else {
                console.log('------------------------------');
                console.log('Host: ' + HOSTNAME + ' Port: ' + PORT);
                console.log('Stream: = ' + stream.uri);
                console.log('------------------------------');

                // start processing the keyboard
                read_and_process_keyboard();
            }
        }
    );

    cam_obj.getPresets({}, // use 'default' profileToken
        // Completion callback function
        // This callback is executed once we have a list of presets
        function (err, stream, xml) {
            if (err) {
                console.log("GetPreset Error "+err);
                return;
            } else {
                // loop over the presets and populate the arrays
                // Do this for the first 9 presets
                console.log("GetPreset Reply");
                var count = 1;
                for(var item in stream) {
                    var name = item;          //key
                    var token = stream[item]; //value
                    // It is possible to have a preset with a blank name so generate a name
                    if (name.length == 0) name='no name ('+token+')';
                    preset_names.push(name);
                    preset_tokens.push(token);

                    // Show first 9 preset names to user
                    if (count < 9) {
                        console.log('Press key '+count+ ' for preset "' + name + '"');
                    count++;
                    }
                }
            }
        }
    );
});

var stop_timer;
var ignore_keypress = false;

function read_and_process_keyboard() {
    // listen for the "keypress" events
    keypress(process.stdin);
    process.stdin.setRawMode(true);
    process.stdin.resume();

    console.log('');
    console.log('Use Cursor Keys to move camera. + and - to zoom. q to quit');

    // keypress handler
    process.stdin.on('keypress', function (ch, key) {

        /* Exit on 'q' or 'Q' or 'CTRL C' */
        if ((key && key.ctrl && key.name == 'c')
             || (key && key.name == 'q')) {
            process.exit();
        }

        if (ignore_keypress) {
            return;
        }

        if (key) {
            console.log('got "keypress"',key.name);
        } else {
            if (ch)console.log('got "keypress character"',ch);
        }


        if      (key && key.name == 'up')    move(0,1,0,'up');
        else if (key && key.name == 'down')  move(0,-1,0,'down');
        else if (key && key.name == 'left')  move(-1,0,0,'left');
        else if (key && key.name == 'right') move(1,0,0,'right');
        else if (ch  && ch       == '-')     move(0,0,-1,'zoom out');
        else if (ch  && ch       == '+')     move(0,0,1,'zoom in');
        // On English keyboards '+' is "Shift and = key"
        // Accept the "=" key as zoom in
        else if (ch  && ch       == '=')     move(0,0,1,'zoom in');
        else if (ch  && ch>='1' && ch <='9') goto_preset(ch);
    });
}


function goto_preset(number) {
    if (number > preset_names.length) {
        console.log ("No preset " + number);
        return;
    }

    console.log('sending goto preset command '+preset_names[number-1]);
    camera.CamFunc().cam_obj.gotoPreset({ preset : preset_tokens[number-1] } ,
        // completion callback function
        function (err, stream, xml) {
            if (err) {
                console.log(err);
            } else {
                console.log('goto preset command sent ');
            }
        });
}

function move(x_speed, y_speed, zoom_speed, msg) {
    // Step 1 - Turn off the keyboard processing (so keypresses do not buffer up)
    // Step 2 - Clear any existing 'stop' timeouts. We will re-schedule a new 'stop' command in this function 
    // Step 3 - Send the Pan/Tilt/Zoom 'move' command.
    // Step 4 - In the callback from the PTZ 'move' command we schedule the ONVIF Stop command to be executed after a short delay and re-enable the keyboard

    // Pause keyboard processing
    ignore_keypress = true;

    // Clear any pending 'stop' commands
    if (stop_timer) clearTimeout(stop_timer);

    // Move the camera
    console.log('sending move command ' + msg);
    camera.cam_obj.continuousMove({x : x_speed,
                y : y_speed,
                zoom : zoom_speed } ,
            // completion callback function
            function (err, stream, xml) {
                if (err) {
                    console.log(err);
                } else {
                    console.log('move command sent '+ msg);
                    // schedule a Stop command to run in the future 
                    stop_timer = setTimeout(stop,STOP_DELAY_MS);
                }
                // Resume keyboard processing
                ignore_keypress = false;
            });
    }


function stop() {
    // send a stop command, stopping Pan/Tilt and stopping zoom
    console.log('sending stop command');
    camera.cam_obj.stop({panTilt: true, zoom: true},
        function (err,stream, xml){
            if (err) {
                console.log(err);
            } else {
                console.log('stop command sent');
            }
        });
}

function PanRight() {
    move(1,0,0,'right');
}

function PanLeft() {
    move(-1,0,0,'left');
}

function TiltUp() {
    move(0,1,0,'up');
}

function TiltDown() {
    move(0,-1,0,'down');
}

function AdjustSpeed(speed){
    x_speed = speed;
    y_speed = speed;
}

function PanFront() {
    goto_preset(1);
}

function PanBack() {
    goto_preset(8);
}

function TiltCenter() {
    goto_preset(1);
}

function Stop() {
    stop();
}

// exported methods for the script.js and other scripts
module.exports = {
    // flashlight: Flashlight,
    // laser: Laser,
    panright: PanRight,
    panleft : PanLeft,
    tiltup: TiltUp,
    tiltdown: TiltDown,
    panfront: PanFront,
    panback: PanBack,
    adjustspeed: AdjustSpeed,
    tiltcenter: TiltCenter,
    stop: Stop
}

The problem is that I'm trying to access cam_obj from within the function CamFunc from within the camera object. I can't quite figure out why it won't let me access the CamFunc method even after attempting several changes to get it to work.

Can anyone tell me how to access a object inside of a function that belongs to an object? I'm relatively new to javascript

in the var camera = new Cam() you are passing object and callback function.by this var cam_obj = this; refer the context of callback function. I think by this question "how to access a object inside of a function that belongs to an object" you are meaning getting callback parameter passed.in that case callback function may contain parameter like this this.CamFunc = function (err) { if (err,obj) { console.log(obj); return; } ;try to console obj — tvankith
– tvankith, Commented Feb 7, 2019 at 19:43

ampyxx · Accepted Answer · 2019-02-07 20:32:42Z

Omg I got it working. Here's the final solution:

function getIPAddress(url) {
    var regex = /[0-9]{1,3}(.[0-9]{1,3})(.[0-9]{1,3})(.[0-9]{1,3})/g;
    return url.match(regex);
}

var HOSTNAME = getIPAddress(localStorage.getItem('ipaddress'))[0],
PORT = 80,
USERNAME = localStorage.getItem('ipusername'),
PASSWORD = localStorage.getItem('ippassword'),
STOP_DELAY_MS = 50;

var Cam = require('./lib/onvif').Cam;
var keypress = require('keypress');
var cam_obj;

new Cam({
    hostname : HOSTNAME,
    username : USERNAME,
    password : PASSWORD,
    port : PORT,
    timeout : 10000
}, function CamFunc(err) {
    if (err) {
        console.log(err);
        return;
    }

    cam_obj = this;

    cam_obj.getStreamUri({
        protocol : 'RTSP'
    },  // Completion callback function
        // This callback is executed once we have a StreamUri
        function (err, stream, xml) {
            if (err) {
                console.log(err);
                return;
            } else {
                console.log('------------------------------');
                console.log('Host: ' + HOSTNAME + ' Port: ' + PORT);
                console.log('Stream: = ' + stream.uri);
                console.log('------------------------------');

                // start processing the keyboard
                read_and_process_keyboard();
            }
        }
    );

    cam_obj.getPresets({}, // use 'default' profileToken
        // Completion callback function
        // This callback is executed once we have a list of presets
        function (err, stream, xml) {
            if (err) {
                console.log("GetPreset Error "+err);
                return;
            } else {
                // loop over the presets and populate the arrays
                // Do this for the first 9 presets
                console.log("GetPreset Reply");
                var count = 1;
                for(var item in stream) {
                    var name = item;          //key
                    var token = stream[item]; //value
                    // It is possible to have a preset with a blank name so generate a name
                    if (name.length == 0) name='no name ('+token+')';
                    preset_names.push(name);
                    preset_tokens.push(token);

                    // Show first 9 preset names to user
                    if (count < 9) {
                        console.log('Press key '+count+ ' for preset "' + name + '"');
                    count++;
                    }
                }
            }
        }
    );
});

var stop_timer;
    var ignore_keypress = false;
    var preset_names = [];
    var preset_tokens = [];

    function read_and_process_keyboard() {
        // listen for the "keypress" events
        keypress(process.stdin);
        process.stdin.setRawMode(true);
        process.stdin.resume();

        console.log('');
        console.log('Use Cursor Keys to move camera. + and - to zoom. q to quit');

        // keypress handler
        process.stdin.on('keypress', function (ch, key) {

            /* Exit on 'q' or 'Q' or 'CTRL C' */
            if ((key && key.ctrl && key.name == 'c')
                 || (key && key.name == 'q')) {
                process.exit();
            }

            if (ignore_keypress) {
                return;
            }

            if (key) {
                console.log('got "keypress"',key.name);
            } else {
                if (ch)console.log('got "keypress character"',ch);
            }


            if      (key && key.name == 'up')    move(0,1,0,'up');
            else if (key && key.name == 'down')  move(0,-1,0,'down');
            else if (key && key.name == 'left')  move(-1,0,0,'left');
            else if (key && key.name == 'right') move(1,0,0,'right');
            else if (ch  && ch       == '-')     move(0,0,-1,'zoom out');
            else if (ch  && ch       == '+')     move(0,0,1,'zoom in');
            // On English keyboards '+' is "Shift and = key"
            // Accept the "=" key as zoom in
            else if (ch  && ch       == '=')     move(0,0,1,'zoom in');
            else if (ch  && ch>='1' && ch <='9') goto_preset(ch);
        });
    }


    function move(x_speed, y_speed, zoom_speed, msg) {
        // Step 1 - Turn off the keyboard processing (so keypresses do not buffer up)
        // Step 2 - Clear any existing 'stop' timeouts. We will re-schedule a new 'stop' command in this function 
        // Step 3 - Send the Pan/Tilt/Zoom 'move' command.
        // Step 4 - In the callback from the PTZ 'move' command we schedule the ONVIF Stop command to be executed after a short delay and re-enable the keyboard

        // Pause keyboard processing
        ignore_keypress = true;

        // Clear any pending 'stop' commands
        if (stop_timer) clearTimeout(stop_timer);

        // Move the camera
        console.log('sending move command ' + msg);
        cam_obj.continuousMove({x : x_speed,
                    y : y_speed,
                    zoom : zoom_speed } ,
                // completion callback function
                function (err, stream, xml) {
                    if (err) {
                        console.log(err);
                    } else {
                        console.log('move command sent '+ msg);
                        // schedule a Stop command to run in the future 
                        stop_timer = setTimeout(stop,STOP_DELAY_MS);
                    }
                    // Resume keyboard processing
                    ignore_keypress = false;
                });
        }


    function stop() {
        // send a stop command, stopping Pan/Tilt and stopping zoom
        console.log('sending stop command');
        cam_obj.stop({panTilt: true, zoom: true},
            function (err,stream, xml){
                if (err) {
                    console.log(err);
                } else {
                    console.log('stop command sent');
                }
            });
    }


    function goto_preset(number) {
        if (number > preset_names.length) {
            console.log ("No preset " + number);
            return;
        }

        console.log('sending goto preset command '+preset_names[number-1]);
        cam_obj.gotoPreset({ preset : preset_tokens[number-1] } ,
            // completion callback function
            function (err, stream, xml) {
                if (err) {
                    console.log(err);
                } else {
                    console.log('goto preset command sent ');
                }
            });
    }

function PanRight() {
    move(1,0,0,'right');
}

function PanLeft() {
    move(-1,0,0,'left');
}

function TiltUp() {
    move(0,1,0,'up');
}

function TiltDown() {
    move(0,-1,0,'down');
}

function AdjustSpeed(speed){
    x_speed = speed;
    y_speed = speed;
}

function PanFront() {
    goto_preset(1);
}

function PanBack() {
    goto_preset(8);
}

function TiltCenter() {
    goto_preset(1);
}

function Stop() {
    stop();
}

// exported methods for the script.js and other scripts
module.exports = {
    // flashlight: Flashlight,
    // laser: Laser,
    panright: PanRight,
    panleft : PanLeft,
    tiltup: TiltUp,
    tiltdown: TiltDown,
    panfront: PanFront,
    panback: PanBack,
    adjustspeed: AdjustSpeed,
    tiltcenter: TiltCenter,
    stop: Stop
}

Thanks for your help guys!

All questions and answers are generally supposed to be useful for any other member who may come across the same or similar problem. Instead of just posting the code, I'd suggest telling specifically what you changed and why. If you don't know why, others can edit your post for further elucidation.

Jon Grant · Accepted Answer · 2019-02-07 19:31:26Z

0

It looks like in the construction of var camera, you are setting this.CamFunc where a parameter would normally go. maybe try just passing the function in without setting this.CamFunc? Or maybe setting this.CamFunc outside of the camera object and passing the function in? Not sure on how the camera object handles the function inside of itself

answered Feb 7, 2019 at 19:31

Jon Grant

495 bronze badges

1 Comment

ampyxx Over a year ago

Here's the original code. I'm trying to modify it so that move, stop, and goto_preset are accessible outside of the function. github.com/agsh/onvif/blob/master/example3.js

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