salesforce.js

var SalesForce = (function () {
    
    // private
    var connection = { foo: 'bar' };  // create the connection here
    
    // public
    return { 
	    
	// expose the connection object
	connection: connection,

	login: (callback) => {
		console.log('login', connection.foo);
    	},
        
        logout: (callback) => {
		console.log('logout', connection.foo);
    	}
    }
    
}());

// usage
SalesForce.login();
SalesForce.logout();
SalesForce.connection;