Can the server get a long-lived access token with the code in `signedRequest`? <p>Is the <code>code</code> property of <code>authResponse.signedRequest</code> (in the Facebook JavaScript API) useful? I'm generating one like this:</p> <pre class="lang-js prettyprint-override"><code>FB.login({ scope: "email" }, function(r) { console.log([ function(d){ return d.split('.')[1]; }, function(d){ return atob(d.replace('-', '+').replace('_', '/')); }, JSON.parse, function(d){ return d.code; } ].reduce( function(acc, f) { return f(acc); }, r.authResponse.signedRequest )); }); </code></pre> <p><a href="https://developers.facebook.com/docs/reference/login/signed-request/" rel="nofollow">The docs</a> say this:</p> <blockquote> <p><code>code</code>: an OAuth Code which can be exchanged for a valid user access token via a <a href="https://developers.facebook.com/docs/authentication/" rel="nofollow">subsequent server-side request</a></p> </blockquote> <p>…but that link redirects to Facebook Login home page. I found the <code>/oauth/access_token</code> endpoint documented <a href="https://developers.facebook.com/docs/facebook-login/access-tokens/" rel="nofollow">here</a>, but it requires a <code>redirect_uri</code> parameter, and there isn't one in this case.</p>