RequireJS works inconsistently

Question

When I press F5 to reload my app sometimes throws errors and sometimes it does not.

I am debugging with Chrome. Sometimes the console reports this error:

Uncaught ReferenceError: unit_directionals is not defined

sometimes throws that a reference is not defined like in this case for jquery: "Uncaught ReferenceError: jQuery is not define"

What can be wrong if i have defined the files in the correct way?

this is the code I have in the main.js pointed in the main index html:

requirejs.config({
    baseUrl: 'js/lib',
    paths:{
        app:'../app',
        models: '../app/models',
        views: '../app/views'
    }
})

requirejs(
    [
        //load lib in this order
        'underscore', 'handlebars', 'jquery','backbone', 'uri',
        //load models, views...
        'app/models/items.model', 'app/models/results.model',
        'app/views/items.view', 'app/views/results.view',
        'app/index'
    ],
    function(jQuery,$,_....) {
        //init app
    }
);

Answer 1

requirejs loads modules async and they can load out of order -- they are not guaranteed to load in the order specified in the require call. If the script is an AMD module, and calls define() with its dependencies, this is not a problem.

However, if the script just uses browser globals and implicit dependencies, like backbone and probably handlebars, then the shim config is needed to properly express the dependencies and export value.