Tentang siswa kelas satu, pembelajaran jarak jauh, dan pemrograman asynchronous

//  
element = $(selector);
element = document.querySelector(selector);

//    
element2 = element.find(selector2);
element2 = element.querySelector(selector2);

//  
element.hide();  //   display: none
element.classList.add('hidden');

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

//   onClick
element.click(e => { ... });
element.onclick = (e) => { ...  }

//  
element.toggleClass(class_name);
element.classList.toggle(class_name);

//  div
div = $("<div>");
div = document.createElement("div");

//   div  element
// (  ,   )
element.append(div);
element.append(div);

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

'use strict';

(function () {
    const selfView = document.querySelector('#self-view'),
        remoteMaster = document.querySelector('#remote-master'),
        remoteSlaves = document.querySelector('#remote-slaves');

    let localStream,
        selfStream = null,
        socket = null,
        selfId = null,
        connections = {};

    // ***********************
    // UserMedia & DOM methods
    // ***********************

    const init = async () => {
        try {
            let stream = await navigator.mediaDevices.getUserMedia({
                audio: true, video: {
                    width: { max: 640 }, height: { max: 480 }
                }
            });
            localStream = stream;

            selfStream = new MediaStream();

            stream.getVideoTracks().forEach(track => {
                selfStream.addTrack(track, stream); // track.kind == 'video'
            });
            selfView.querySelector('video').srcObject = selfStream;

        } catch (e) {
            document.querySelector('#self-view').innerHTML =
                '<i>     </i>';
            console.error('Local stream not found: ', e);
        }
        wsInit();
    }

    const createRemoteView = (id, username) => {
        let iDiv = document.querySelector('#pc' + id);
        if (!iDiv) {
            iDiv = document.createElement('div');
            iDiv.className = 'remote-view';
            iDiv.id = 'pc' + id;

            let iVideo = document.createElement('video');
            iVideo.setAttribute('autoplay', 'true');
            iVideo.setAttribute('playsinline', 'true');

            let iLabel = document.createElement('span');

            iDiv.append(iVideo);
            iDiv.append(iLabel);

            if (!remoteMaster.querySelector('video')) {
                remoteMaster.append(iDiv);
                iLabel.textContent = '';
            } else {
                remoteSlaves.append(iDiv);
                iLabel.textContent = username;
            }
            remoteMaster.style.removeProperty('display');
        }
    }

    // *******************************
    // Signaling (Web Socket) methods
    // *******************************

    const wsInit = () => {
        socket = new WebSocket(SIGNALING_SERVER_URL);

        socket.onopen = function (e) {
            log('[socket open]  ');
        }

        socket.onmessage = function (event) {
            log('[socket message]    ', event);

            wsHandle(event.data);
        }

        socket.onclose = function (event) {
            if (event.wasClean) {
                log('[close]   , ' +
                    `=${event.code} =${event.reason}`);
            } else {
                log('[socket close]  ', event);
            }
            clearInterval(socket.timer);
        }

        socket.onerror = function (error) {
            logError('[socket error]', error);
        }

        socket.timer = setInterval(() => {
            socket.send('heartbeat');
        }, 10000);
    }

    const wsHandle = async (data) => {
        if (!data) {
            return;
        }
        try {
            data = JSON.parse(data);
        } catch (e) {
            return;
        }

        switch (data.type) {
            case 'handshake':
                selfId = data.uid;
                if (!Object.keys(data.users).length) {
                    createRemoteView(selfId, '');
                    remoteMaster.querySelector('video').srcObject =
                        selfStream;
                    selfView.remove();
                    break;
                } else {
                    selfView.style.removeProperty('display');
                }
                for (let id in data.users) {
                    await pcCreate(id, data.users[id]);
                }
                break;
            case 'offer':
                await wsHandleOffer(data);
                break;
            case 'answer':
                await wsHandleAnswer(data)
                break;
            case 'candidate':
                await wsHandleICECandidate(data);
                break;
            default:
                break;
        }
    }

    const wsHandleOffer = async (data) => {
        let pc = null;

        if (!connections[data.src]) {
            await pcCreate(data.src, data.username);
        }

        pc = connections[data.src].pc;

        // We need to set the remote description to the received SDP offer
        // so that our local WebRTC layer knows how to talk to the caller.
        let desc = new RTCSessionDescription(data.sdp);

        pc.setRemoteDescription(desc).catch(error => {
            logError('handleOffer', error);
        });

        await pc.setLocalDescription(await pc.createAnswer());

        wsSend({
            type: 'answer',
            target: data.src,
            sdp: pc.localDescription
        });

        connections[data.src].pc = pc; // ???
    }

    const wsHandleAnswer = async (data) => {
        log('*** Call recipient has accepted our call, answer:', data);

        let pc = connections[data.src].pc;

        // Configure the remote description,
        // which is the SDP payload in our 'answer' message.

        let desc = new RTCSessionDescription(data.sdp);
        await pc.setRemoteDescription(desc).catch((error) => {
            logError('handleAnswer', error);
        });
    }

    const wsHandleICECandidate = async (data) => {
        let pc = connections[data.src].pc;

        let candidate = new RTCIceCandidate(data.candidate);

        log('*** Adding received ICE candidate', candidate);

        pc.addIceCandidate(candidate).catch(error => {
            logError('handleICECandidate', error);
        });
    }

    const wsSend = (data) => {
        if (socket.readyState !== WebSocket.OPEN) {
            return;
        }
        socket.send(JSON.stringify(data));
    }

    // ***********************
    // Peer Connection methods
    // ***********************

    const pcCreate = async (id, username) => {
        if (connections[id]) {
            return;
        }
        try {
            let pc = new RTCPeerConnection(PC_CONFIG);

            pc.onicecandidate = (event) =>
                pcOnIceCandidate(event, id);
            pc.oniceconnectionstatechange = (event) =>
                pcOnIceConnectionStateChange(event, id);
            pc.onsignalingstatechange =  (event) =>
                pcOnSignalingStateChangeEvent(event, id);
            pc.onnegotiationneeded = (event) =>
                pcOnNegotiationNeeded(event, id);
            pc.ontrack = (event) =>
                pcOnTrack(event, id);

            connections[id] = {
                pc: pc,
                username: username
            }

            if (localStream) {
                try {
                    localStream.getTracks().forEach(
                        (track) => connections[id].pc.addTransceiver(track, {
                            streams: [localStream]
                        })
                    );
                } catch (err) {
                    logError(err);
                }
            } else {
                // Start negotiation to listen remote stream only
                pcOnNegotiationNeeded(null, id);
            }
            createRemoteView(id, username);
        } catch (error) {
            logError('Peer: Connection failed', error);
        }
    }

    const pcOnTrack = (event, id) => {
        let iVideo = document.querySelector('#pc' + id + ' video');
        iVideo.srcObject = event.streams[0];
    }

    const pcOnIceCandidate = (event, id) => {
        let pc = connections[id].pc;

        if (event.candidate && pc.remoteDescription) {
            log('*** Outgoing ICE candidate: ' + event.candidate);
            wsSend({
                type: 'candidate',
                target: id,
                candidate: event.candidate
            });
        }
    }

    const pcOnNegotiationNeeded = async (event, id) => {
        let pc = connections[id].pc;
        try {
            const offer = await pc.createOffer();

            // If the connection hasn't yet achieved the "stable" state,
            // return to the caller. Another negotiationneeded event
            // will be fired when the state stabilizes.
            if (pc.signalingState != 'stable') {
                return;
            }

            // Establish the offer as the local peer's current
            // description.
            await pc.setLocalDescription(offer);

            // Send the offer to the remote peer.
            wsSend({
                type: 'offer',
                target: id,
                sdp: pc.localDescription
            });
        } catch(err) {
            logError('*** The following error occurred while handling' +
                ' the negotiationneeded event:', err);
        };
    }

    const pcOnIceConnectionStateChange = (event, id) => {
        let pc = connections[id].pc;
        switch (pc.iceConnectionState) {
            case 'closed':
            case 'failed':
            case 'disconnected':
                pcClose(id);
                break;
        }
    }

    const pcOnSignalingStateChangeEvent = (event, id) => {
        let pc = connections[id].pc;

        log('*** WebRTC signaling state changed to: ' + pc.signalingState);

        switch (pc.signalingState) {
            case 'closed':
                pcClose(id);
                break;
        }
    }

    const pcClose = (id) => {
        let remoteView = document.querySelector('#pc' + id);

        if (connections[id]) {
            let pc = connections[id].pc;
            pc.close();
            delete connections[id];
        }
        if (remoteView) {
            remoteView.remove();
        }
    }

    // *******
    // Helpers
    // *******

    const log = (msg, data) => {
        if (!data) {
            data = ''
        }
        console.log(msg, data);
    }

    const logError = (msg, data) => {
        if (!data) {
            data = ''
        }
        console.error(msg, data);
    }

    init();
})();

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

import json
from aiohttp.web import WebSocketResponse, Response
from aiohttp import WSMsgType
from uuid import uuid1
from lib.views import BaseView


class WebSocket(BaseView):
    """ Process WS connections """

    async def get(self):
        username = self.request['current_user'].firstname or ''

        room_id = self.request.match_info.get('room_id')

        if room_id != 'test_room' and
            self.request['current_user'].is_anonymous:
            self.raise_error('forbidden')  # @TODO: send 4000

        if (self.request.headers.get('connection', '').lower() != 'upgrade' or
            self.request.headers.get('upgrade', '').lower() != 'websocket'):
            return Response(text=self.request.path)  # ???

        self.ws = WebSocketResponse()
        await self.ws.prepare(self.request)

        self.uid = str(uuid1())

        if room_id not in self.request.app['web_sockets']:
            self.request.app['web_sockets'][room_id] = {}

        self.room = self.request.app['web_sockets'][room_id]

        users = {}
        for id, data in self.room.items():
            users[id] = data['name']

        ip = self.request.headers.get(
            'X-FORWARDED-FOR',
            self.request.headers.get('X-REAL-IP',
            self.request.remote))

        msg = {
            'type': 'handshake',
            'uid': str(self.uid),
            'users': users, 'ip': ip}
        await self.ws.send_str(json.dumps(msg, ensure_ascii=False))

        self.room[self.uid] = {'name': username, 'ws': self.ws}

        try:
            async for msg in self.ws:
                if msg.type == WSMsgType.TEXT:
                    if msg.data == 'heartbeat':
                        print('---heartbeat---')
                        continue

                    try:
                        msg_data = json.loads(msg.data)

                        if 'target' not in msg_data or
                            msg_data['target'] not in self.room:
                            continue

                        msg_data['src'] = self.uid

                        if 'type' in msg_data and 'target' in msg_data:
                            if msg_data['type'] == 'offer':
                                msg_data['username'] = username
                        else:
                            print('INVALID DATA:', msg_data)
                    except Exception as e:
                        print('INVALID JSON', e, msg)

                    try:
                        await self.room[msg_data['target']]['ws'].send_json(
                            msg_data);
                    except Exception as e:
                        if 'target' in msg_data:
                            self.room.pop(msg_data['target'])

        finally:
            self.room.pop(self.uid)

        return self.ws