Question

I have a function, authenticate() that uses $post() to retrieve a session key from my server. I believe $post is an asynchronous call. Whenever I perform any action in my script, I want to ensure that I have a sessionKey, and if I do not have a sessionKey I want to authenticate(). My problem is how do I run performTask() after I have called authenicate()?

function foo() {
    if (sessionKey) {
        performTask();
    } else {
        authenciate();
        performTask();
    }
}

function authenticate() {       
    $.post(url, function(data) {
        sessionKey = data.sessionKey;
    });
}

EDIT: I also do not want to put in authenticate()’s callback function performTask() as authenticate() will be called from several different functions.

Answer 1

You can pass in a callback to the authenticate method. If authenticate is called from 20 different places, you can pass in 20 different callback methods.

function foo() {
    if (sessionKey) {
        performTask();
    } else {
        authenciate(function() {
           performTask();
        });
    }
}

function authenticate(callback) {       
    $.post(url, function(data) {
        sessionKey = data.sessionKey;
        if (callback) callback();
    });
}