main.js

// Abbreviated version from https://github.com/Alex-Wauters/firebase-auth-azure-ad/blob/master/main.js
firebase.auth().onAuthStateChanged(function (user) {
    if (user) {
        console.log('User is logged in');
        startApp();
    } else {
        const url = window.location.href;
        if (url.indexOf('jwt=') > -1) {  // The minted firebase token from Auth function
            const token = url.substr( url.indexOf('jwt=') + 4);
            firebase.auth().signInWithCustomToken(token)
                .then((user) => {
                    window.location.href="/";
                })
                .catch(function (error) {
                    // Handle Errors here.
                });
        } else { // User not authenticated and no custom token present. Redirect to Azure AD for authentication token
            let redirectUrl = "/auth"; //TODO: Redirect to the URL of your auth function
            if (window.location.port === "5000") { // Adjust the requested redirectUri for local development
                redirectUrl = redirectUrl + "&redirect_uri=http%3A%2F%2Flocalhost%3A5000%2Fauth";
            }
            window.location.href = redirectUrl;
        }
    }
});

function startApp() { //Load front-end application
    new Vue({
        el: '#app',
        template: '<App/>',
        components: {App}
    })
}