js.html

<script type="text/javascript"
        data-app-id="SPECIFY APP CLIENT ID HERE"
        src="https://assets.yammer.com/assets/platform_js_sdk.js"></script>
<script>
    yam.getLoginStatus({ token: 'SPECIFY A TOKEN ASSOCIATED WITH APP CLIENT ID' },
    function (response) {
        if (response.authResponse) {
            alert("logged in");
            console.dir(response);
        }
        else {
            alert("logged out");
            yam.login(function (response) {
                if (response.authResponse) {
                    console.dir(response);
                }
            });
        }
    }
    );
</script>