Handle credential response
You can set a JavaScript function in the data-callback attribute to handle the
returned credential response. See the following code snippet:
<div id="g_id_onload"
data-client_id="YOUR_GOOGLE_CLIENT_ID"
data-callback="handleCredentialResponse">
</div>
<script>
function handleCredentialResponse(response) {
// decodeJwtResponse() is a custom function defined by you
// to decode the credential response.
const responsePayload = decodeJwtResponse(response.credential);
console.log("ID: " + responsePayload.sub);
console.log('Full Name: ' + responsePayload.name);
console.log('Given Name: ' + responsePayload.given_name);
console.log('Family Name: ' + responsePayload.family_name);
console.log("Image URL: " + responsePayload.picture);
console.log("Email: " + responsePayload.email);
}
</script>
You can validate and decode the JWT credential by using a JWT-decoding library for your language. You should also verify the Google ID token on your server side.