How to detect when facebook’s FB.init is complete

Update on Jan 04, 2012

It seems like you can’t just call FB-dependent methods (for example FB.getAuthResponse()) right after FB.init() like before, as FB.init() seems to be asynchronous now. Wrapping your code into FB.getLoginStatus() response seems to do the trick of detecting when API is fully ready:

window.fbAsyncInit = function() {
    FB.init({
        //...
    });

    FB.getLoginStatus(function(response){
        runFbInitCriticalCode(); 
    });

};  

or if using fbEnsureInit() implementation from below:

window.fbAsyncInit = function() {
    FB.init({
        //...
    });

    FB.getLoginStatus(function(response){
        fbApiInit = true;
    });

};  

---

Original Post:

If you want to just run some script when FB is initialized you can put some callback function inside fbAsyncInit:

  window.fbAsyncInit = function() {
    FB.init({
      appId  : '<?php echo $conf['fb']['appid']; ?>',
      status : true, // check login status
      cookie : true, // enable cookies to allow the server to access the session
      xfbml  : true  // parse XFBML
    });
    FB.Canvas.setAutoResize();

    runFbInitCriticalCode(); //function that contains FB init critical code
  };

If you want exact replacement of FB.ensureInit then you would have to write something on your own as there is no official replacement (big mistake imo). Here is what I use:

  window.fbAsyncInit = function() {
    FB.init({
      appId  : '<?php echo $conf['fb']['appid']; ?>',
      status : true, // check login status
      cookie : true, // enable cookies to allow the server to access the session
      xfbml  : true  // parse XFBML
    });
    FB.Canvas.setAutoResize();

    fbApiInit = true; //init flag
  };

  function fbEnsureInit(callback) {
        if(!window.fbApiInit) {
            setTimeout(function() {fbEnsureInit(callback);}, 50);
        } else {
            if(callback) {
                callback();
            }
        }
    }

Usage:

fbEnsureInit(function() {
    console.log("this will be run once FB is initialized");
});