Detecting logout event of {{> loginButtons}} in Meteor - meteor

Question

I am working on project using meteor 0.8.2 and i have added "accounts-ui" and "accounts-password" for login functionality in the project. The login module works perfect. I am curious to know that, How to detect the logout event? Is there any function like,
Template.loginButtons.events({
'click .logout'=function(e)
{
console.log("I logged out!");
}
});

Answer 1

There is no official callback like Meteor.onLogout, but the standard way to handle this is as follow :
In templates :
{{#if currentUser}}
<p>logged in</p>
{{else}}
<p>logged out</p>
{{/if}}
currentUser is a standard Spacebars helper that simply returns the current user, if there is none, it returns a falsy value.
http://docs.meteor.com/#template_currentuser
In javascript :
Deps.autorun(function(computation){
var currentUser=Meteor.user();
if(currentUser){
console.log("logged in");
}
else if(!computation.firstRun){
console.log("logged out");
}
});
We can mirror the tempate code by registering a new Deps.Computation that references Meteor.user() which happens to be a reactive data-source returning the current user.
Whenever this variable change (ie on login/logout) the computation will rerun and we can inject our own custom code to handle login/logout in our webapp.
EDIT : as Neil said, the computation is run immediately following the declaration, in a state where the login resuming process maybe uncomplete resulting in a useless systematic logout detection on app startup, which might be an inconvenience.
We can detect the first run of the computation using the built in firstRun property and execute the logout logic only when it's NOT the first run.

Answer 2

You want watch the reactive function Meteor.userId for changes using Deps.autorun.
var started = false;
Deps.autorun(function () {
if (started && !Meteor.userId())
console.log('I logged out!');
started = true;
});
The function runs once immediately so started prevents that from being interpreted as a logout.