auth-start.html

<html>
<head>
    <title>Authentication</title>
</head>
<body>
    <script src="https://statics.teams.microsoft.com/sdk/v1.0/js/MicrosoftTeams.min.js"></script>
    <script src="adal.js"></script>
    <script src="auth-config.js"></script>
    <script type="text/javascript">
        microsoftTeams.initialize();

        // Parse query parameters
        let queryParams = {};
        location.search.substr(1).split("&").forEach(function(item) {
            let s = item.split("="),
            k = s[0],
            v = s[1] && decodeURIComponent(s[1]);
            queryParams[k] = v;
        });

        let upn = queryParams["upn"];
        if (upn) {
            config.extraQueryParameters = "scope=openid+profile&login_hint=" + encodeURIComponent(upn);
        } else {
            config.extraQueryParameters = "scope=openid+profile";              
        }

        // Use a custom displayCall function to add extra query parameters to the url before navigating to it
        config.displayCall = function (urlNavigate) {
            if (urlNavigate) {
                if (config.extraQueryParameters) {
                    urlNavigate += "&" + config.extraQueryParameters;
                }
                window.location.replace(urlNavigate);
            }
        }

        console.log("extraQueryParameters: " + config.extraQueryParameters);
        console.log("Starting login flow");
        let authContext = new AuthenticationContext(config);
        authContext.login();
    </script>
</body>
</html>