Listeners provide a way to automatically respond to changes in the current
user's Sign-In session. For example, after your startup method initializes the
Google Sign-In auth2 object, you can set up listeners to respond to events
like auth2.isSignedIn
state changes, or changes in auth2.currentUser
.
The following code demonstrates using the 2.0 client method listen()
to respond to changes in auth2.isSignedIn
and auth2.currentUser
.
var
auth2
;
//
The
Sign
-
In
object
.
var
googleUser
;
//
The
current
user
.
/**
*
Calls
startAuth
after
Sign
in
V2
finishes
setting
up
.
*/
var
appStart
=
function
()
{
gapi
.
load
(
'auth2'
,
initSigninV2
);
};
/**
*
Initializes
Signin
v2
and
sets
up
listeners
.
*/
var
initSigninV2
=
function
()
{
auth2
=
gapi
.
auth2
.
init
({
client_id
:
'CLIENT_ID.apps.googleusercontent.com'
,
scope
:
'profile'
});
//
Listen
for
sign
-
in
state
changes
.
auth2
.
isSignedIn
.
listen
(
signinChanged
);
//
Listen
for
changes
to
current
user
.
auth2
.
currentUser
.
listen
(
userChanged
);
//
Sign
in
the
user
if
they
are
currently
signed
in
.
if
(
auth2
.
isSignedIn
.
get
()
==
true
)
{
auth2
.
signIn
();
}
//
Start
with
the
current
live
values
.
refreshValues
();
};
/**
*
Listener
method
for
sign
-
out
live
value
.
*
*
@
param
{
boolean
}
val
the
updated
signed
out
state
.
*/
var
signinChanged
=
function
(
val
)
{
console
.
log
(
'Signin state changed to '
,
val
);
document
.
getElementById
(
'signed-in-cell'
)
.
innerText
=
val
;
};
/**
*
Listener
method
for
when
the
user
changes
.
*
*
@
param
{
GoogleUser
}
user
the
updated
user
.
*/
var
userChanged
=
function
(
user
)
{
console
.
log
(
'User now: '
,
user
);
googleUser
=
user
;
updateGoogleUser
();
document
.
getElementById
(
'curr-user-cell'
)
.
innerText
=
JSON
.
stringify
(
user
,
undefined
,
2
);
};
/**
*
Updates
the
properties
in
the
Google
User
table
using
the
current
user
.
*/
var
updateGoogleUser
=
function
()
{
if
(
googleUser
)
{
document
.
getElementById
(
'user-id'
)
.
innerText
=
googleUser
.
getId
();
document
.
getElementById
(
'user-scopes'
)
.
innerText
=
googleUser
.
getGrantedScopes
();
document
.
getElementById
(
'auth-response'
)
.
innerText
=
JSON
.
stringify
(
googleUser
.
getAuthResponse
(),
undefined
,
2
);
}
else
{
document
.
getElementById
(
'user-id'
)
.
innerText
=
'--'
;
document
.
getElementById
(
'user-scopes'
)
.
innerText
=
'--'
;
document
.
getElementById
(
'auth-response'
)
.
innerText
=
'--'
;
}
};
/**
*
Retrieves
the
current
user
and
signed
in
states
from
the
GoogleAuth
*
object
.
*/
var
refreshValues
=
function
()
{
if
(
auth2
){
console
.
log
(
'Refreshing values...'
);
googleUser
=
auth2
.
currentUser
.
get
();
document
.
getElementById
(
'curr-user-cell'
)
.
innerText
=
JSON
.
stringify
(
googleUser
,
undefined
,
2
);
document
.
getElementById
(
'signed-in-cell'
)
.
innerText
=
auth2
.
isSignedIn
.
get
();
updateGoogleUser
();
}
}
