This module encapsulates code which is responsible for room chat

1. Wrapper function

createChat() code

Encapsulates chat code inside the closure

const createChat = function(room, messages, input, sendButton) {

2. Local variables

code

Define local variables - SFU constants and colours

const constants = SFU.constants;
const chatSelfColour = "green";
const chatTextColour = "black";
const chatOtherColour = "red";
const chatEventColour = "navy";

3. Subscribe to room events

code

Subscribe to room events that are related to chat functionality

    room.on(constants.SFU_ROOM_EVENT.MESSAGE, function(e) {
        appendMessage({
            userId: getUserId(e.message),
            nickName: getNickName(e.message),
            message: getMessage(e.message)
        }, chatOtherColour, chatTextColour);
    }).on(constants.SFU_ROOM_EVENT.JOINED, function(e) {
        appendMessage({
            userId: getShortUserId(e.userId),
            nickName: e.name,
            message: e.type
        }, chatOtherColour, chatEventColour);
    }).on(constants.SFU_ROOM_EVENT.LEFT, function(e) {
        appendMessage({
            userId: getShortUserId(e.userId),
            nickName: e.name,
            message: e.type
        }, chatOtherColour, chatEventColour);
    });

SFU_ROOM_EVENT.MESSAGE

Subscribe to new message event. Once received display it in local chat

code

    room.on(constants.SFU_ROOM_EVENT.MESSAGE, function(e) {
        appendMessage({
            userId: getUserId(e.message),
            nickName: getNickName(e.message),
            message: getMessage(e.message)
        }, chatOtherColour, chatTextColour);
        ...
    });

SFU_ROOM_EVENT.JOINED

Subscribe to new participant event. Once received display a special notification inside the local chat

code

    room.on(constants.SFU_ROOM_EVENT.MESSAGE, function(e) {
        ...
    }).on(constants.SFU_ROOM_EVENT.JOINED, function(e) {
        appendMessage({
            userId: getShortUserId(e.userId),
            nickName: e.name,
            message: e.type
        }, chatOtherColour, chatEventColour);
        ...
    });

SFU_ROOM_EVENT.LEFT

Subscribe to participant left event. Once received display a special notification inside the local chat

code

    room.on(constants.SFU_ROOM_EVENT.MESSAGE, function(e) {
        ...
    }).on(constants.SFU_ROOM_EVENT.LEFT, function(e) {
        appendMessage({
            userId: getShortUserId(e.userId),
            nickName: e.name,
            message: e.type
        }, chatOtherColour, chatEventColour);
    });

4. Send message to other participants

sendMessage() code

Define the sendMessage function which will be responsible for parsing input, sending it to server and displaying it in the local chat as a message

Note that messages is sent using WebRTC data channels

    const sendMessage = async function() {
        let message = input.value;
        input.value = "";
        await room.sendMessage(message);
        appendMessage({
            userId: getShortUserId(room.userId()),
            nickName: nickName.value,
            message: message
        }, chatSelfColour, chatTextColour);
    }

Tie send button to sendMessage function

code

sendButton.addEventListener("click", sendMessage);

Give ability to send message by pressing Enter

code

input.onkeyup = function(e) {
    if (e.keyCode === 13) {
        if (e.shiftKey) {

        } else {
            sendMessage();
        }
        return false;
    }
}

5. Display chat messages locally

Define function that will take care of formatting and displaying messages in local chat

appendMessage() code

    const appendMessage = function(msg, nickColour, msgColour) {
        let message = document.createElement('div');
        message.setAttribute("class","message");
        messages.appendChild(message);
        let nickDiv = document.createElement('div');
        nickDiv.style.color = nickColour;
        nickDiv.innerText = getChatTimestamp() + " " + msg.nickName + "#" + msg.userId + ":";
        message.appendChild(nickDiv);
        let msgDiv = document.createElement('div');
        msgDiv.style.color = msgColour;
        msgDiv.innerText = msg.message;
        message.appendChild(msgDiv);
        scrollToBottom();
    }

Scroll to bottom helper

scrollToBottom() code

const scrollToBottom = function() {
    messages.scrollTop = messages.scrollHeight;
}

Timestamp helper

getTimeStamp() code

const getChatTimestamp = function() {
    let currentdate = new Date();
    return currentdate.getHours() + ":" + currentdate.getMinutes() + ":" + currentdate.getSeconds();
}

6. Get sender user id from the message

getUserId() code

    const getUserId = function(msgData) {
        let userId = "unknown";
        if (msgData.userId) {
            userId = msgData.userId;
        } else if (msgData.message.userId) {
            userId = msgData.message.userId;
        }
        return getShortUserId(userId);
    }

7. Get sender nickname from the message

getNickName() code

    const getNickName = function(msgData) {
        let nickName = "unknown";
        if (msgData.nickName) {
            nickName = msgData.nickName;
        } else if (msgData.message.nickName) {
            nickName = msgData.message.nickName;
        }
        return nickName;
    }

8. Get the message payload

getMessage() code

    const getMessage = function(msgData) {
        let message = "";
        if (msgData.message) {
            message = JSON.parse(msgData.message).payload;
        }
        return message;
    }