index.html

<!DOCTYPE html>
<html>
<head>
    <script type="text/javascript" src="https://alcdn.msauth.net/browser/2.30.0/js/msal-browser.min.js"></script>
    <script>
        const msalConfig = {
            auth: {
                clientId: "1215945f-ad89-4331-92f6-0088940bc5c6"
            }
        }

        const msalInstance = new msal.PublicClientApplication(msalConfig);
        // msalInstance.loginPopup({
        //     // redirectUri: "http://localhost:8000/outlook.html",
        //     scopes: ['mail.read']
        // });

        msalInstance.acquireTokenPopup({
            scopes: ['Mail.Read']
        }).then(tokenResponse => {
            // Do something with the tokenResponse
            console.log(tokenResponse);
            makeMailRequest(tokenResponse);
        }).catch(error => {
            console.log(error);
        });

        function makeMailRequest(tokenResponse) {
            var headers = new Headers();
            var bearer = "Bearer " + tokenResponse.accessToken;
            headers.append("Authorization", bearer);
            var options = {
                    method: "GET",
                    headers: headers
            };
            var graphEndpoint = "https://graph.microsoft.com/v1.0/me/messages";

            fetch(graphEndpoint, options)
                .then(resp => {
                    console.log(resp);
                });
        }
    </script>
</head>
<body>

</body>
</html>