util.js

util.js module contais a various helper functions

Analyzing the source code

To analyze the source code take the util.js module version available here

1. Exclude a video codecs from SDP

stripCodecs() code

const stripCodecs = function(sdp, codecs) {
    if (!codecs.length) return sdp;
    var sdpArray = sdp.split("\n");
    var codecsArray = codecs.split(",");

    //search and delete codecs line
    var pt = [];
    var i;
    for (var p = 0; p < codecsArray.length; p++) {
        console.log("Searching for codec " + codecsArray[p]);
        for (i = 0; i < sdpArray.length; i++) {
            if (sdpArray[i].search(new RegExp(codecsArray[p],'i')) !== -1 && sdpArray[i].indexOf("a=rtpmap") === 0) {
                console.log(codecsArray[p] + " detected");
                pt.push(sdpArray[i].match(/[0-9]+/)[0]);
                sdpArray[i] = "";
            }
        }
    }
    if (pt.length) {
        //searching for fmtp
        for (p = 0; p < pt.length; p++) {
            for (i = 0; i < sdpArray.length; i++) {
                if (sdpArray[i].search("a=fmtp:" + pt[p]) !== -1 || sdpArray[i].search("a=rtcp-fb:" + pt[p]) !== -1) {
                    sdpArray[i] = "";
                }
            }
        }

        //delete entries from m= line
        for (i = 0; i < sdpArray.length; i++) {
            if (sdpArray[i].search("m=audio") !== -1 || sdpArray[i].search("m=video") !== -1) {
                var mLineSplitted = sdpArray[i].split(" ");
                var newMLine = "";
                for (var m = 0; m < mLineSplitted.length; m++) {
                    if (pt.indexOf(mLineSplitted[m].trim()) === -1 || m <= 2) {
                        newMLine += mLineSplitted[m];
                        if (m < mLineSplitted.length - 1) {
                            newMLine = newMLine + " ";
                        }
                    }
                }
                sdpArray[i] = newMLine;
            }
        }
    }

    //normalize sdp after modifications
    var result = "";
    for (i = 0; i < sdpArray.length; i++) {
        if (sdpArray[i] !== "") {
            result += sdpArray[i] + "\n";
        }
    }
    return result;
}

2. Exclude all the video codecs from SDP but a certain codec

stripVideoCodecsExcept() code

const stripVideoCodecsExcept = function (sdp, codec) {
    let actualStripCodec = "rtx";
    if (codec === "VP8") {
        actualStripCodec += ",H264";
    } else if (codec === "H264") {
        actualStripCodec += ",VP8";
    } else {
        return sdp;
    }
    return stripCodecs(sdp, actualStripCodec);
}

3. Construct a server websocket URL

setURL() code

const setURL = function () {
    var proto;
    var url;
    var port;
    if (window.location.protocol == "http:") {
        proto = "ws://";
        port = "8080";
    } else {
        proto = "wss://";
        port = "8443";
    }

    url = proto + window.location.hostname + ":" + port;
    return url;
}

4. Get a parameter from URL

getUrlParam() code

const getUrlParam = function (name) {
    var url = window.location.href;
    name = name.replace(/[\[\]]/g, "\\$&");
    var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
        results = regex.exec(url);
    if (!results) return null;
    if (!results[2]) return '';
    return decodeURIComponent(results[2].replace(/\+/g, " "));
}

5. Generate an UUID

createUUID() code

const createUUID = function (length) {
    var s = [];
    var hexDigits = "0123456789abcdef";
    for (var i = 0; i < 36; i++) {
        s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
    }
    s[14] = "4";
    s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1);
    s[8] = s[13] = s[18] = s[23] = "-";

    var uuid = s.join("");

    return uuid.substring(0, length);
}

6. Browser detection object

Browser() code

const Browser = function() {
    const isIE = function () {
        return /*@cc_on!@*/false || !!document.documentMode;
    }

    const isFirefox = function () {
        return typeof InstallTrigger !== 'undefined';
    }

    const isChrome = function () {
        return !!window.chrome && /Chrome/.test(navigator.userAgent) && /Google Inc/.test(navigator.vendor) && !/OPR/.test(navigator.userAgent);
    }

    const isEdge =  function () {
        return !this.isIE() && !!window.StyleMedia;
    }

    const isOpera = function () {
        return (!!window.opr && !!opr.addons) || !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0;
    }

    const isiOS = function () {
        return /iPad|iPhone|iPod/.test(navigator.userAgent) && !window.MSStream;
    }

    const isSafari = function () {
        let userAgent = navigator.userAgent.toLowerCase();
        return /(safari|applewebkit)/i.test(userAgent) && !userAgent.includes("chrome") && !userAgent.includes("android");
    }

    const isAndroid = function () {
        return navigator.userAgent.toLowerCase().indexOf("android") > -1;
    }

    const isSafariWebRTC = function () {
        return navigator.mediaDevices && this.isSafari();
    }

    const isSamsungBrowser = function () {
        return /SamsungBrowser/i.test(navigator.userAgent);
    }

    const isAndroidFirefox = function () {
        return this.isAndroid() && /Firefox/i.test(navigator.userAgent);
    }

    const isMobile = function () {
        return this.isAndroid() || this.isiOS();
    }

    return {
        isIE: isIE,
        isFirefox: isFirefox,
        isChrome: isChrome,
        isEdge: isEdge,
        isOpera: isOpera,
        isSafari: isSafari,
        isSafariWebRTC: isSafariWebRTC,
        isSamsungBrowser: isSamsungBrowser,
        isAndroid: isAndroid,
        isiOS: isiOS,
        isAndroidFirefox: isAndroidFirefox,
        isMobile: isMobile
    }
}

7. Workaround to play an audio in Safari 12 using a preloader

playFirstSound() code

const playFirstSound = function (parent, preloader) {
    return new Promise(function (resolve, reject) {
        let audio = document.createElement("audio");
        audio.controls = "controls";
        audio.muted = true;
        audio.hidden = true;
        audio.preload = "auto";
        audio.type="audio/mpeg";
        if (preloader) {
            audio.src = preloader;
            parent.appendChild(audio);
            audio.play().then(function() {
                audio.remove();
                resolve();
            }).catch(function (e) {
                console.error("Can't play preloader: " + e);
                reject();
            });
            return;
        }
        resolve();
    });
}

8. Get a short meeting room participant Id

getShortUserId() code

const getShortUserId = function (userId) {
    return userId.substring(0, 4);
}