First, I wanted to be sure that all the firebase scripts are loaded and they are loaded in the proper order.

I solved this in a bit of a rudimentary way but it works :)

```
var my_firebase_init = function(){

    firebase.initializeApp(my_firebase_config);
    firebase.auth().languageCode = my_lang;

    console.log('FIREBASE INIT OK');

}

var firebase_version = 'https://www.gstatic.com/firebasejs/4.6.2/';

var scripts = [
    firebase_version+'firebase.js',
    firebase_version+'firebase-app.js',
    firebase_version+'firebase-auth.js',
    'my_firebase_init'

];

var script_loaded = [];

var deferred = new $.Deferred(),

pipe = deferred;

$.each(scripts , function(index, script) {
    pipe = pipe.pipe(function() {

        if(script == 'my_firebase_init'){
            if(script_loaded[0] && script_loaded[1] && script_loaded[2]){
                my_firebase_init();
            }
            return;
        }

        return $.getScript(script)
            .done(function( script, textStatus ) {
                 script_loaded[index] = true
            })
            .fail(function( jqxhr, settings, exception ) {
                 script_loaded[index] = false
        });                 
    });
});

deferred.resolve(); 

```

Now I can see `console.log('FIREBASE INIT OK')`

The next I try to use recaptcha like:

```
window.recaptchaVerifier = new firebase.auth.RecaptchaVerifier('id_container_recaptcha', {
    'size': 'invisible',
    'callback': function(response) {
        // reCAPTCHA solved, allow user to do action.
        // ...   
    },
    'expired-callback': function() {
         // Response expired. Ask user to solve reCAPTCHA again.
         // ...
    }

});

```

This is working good but from time to time I get this error:

> 
> No firebase.app.App instance is currently initialized
> 
> 
> 

I noticed that if I wait a bit and try again ... works good!

So my question is :
**How I can check if firebase.app.App is initialized ?**