Question

What’s the difference between

var myView = function () {
//something goes here
};

and

var myView = function () {
//something goes here
    return {
        a: x,
        b: y
}();

I think the first snippet creates a “dynamic” class, so that you can say

var anotherView = new myView();

and the second snippet is similar to a singleton “dynamic” object, but I’m not very sure.

Answer 1

Javascript uses prototypal inheritance, so there are no classes per se. Everything is an object; it’s just that some objects have a common parent object whose methods/variables will be found when name resolution looks up the prototype chain.

Your first code snippet creates an object called myView whose type is a function. Your second snippet defines an anonymous method which returns an object (with two properties, a and b) and then immediately calls this method, assigning the result to myView. So in this second case, myView is an object with two self-defined properties.

It may help you to read Douglas Crockford’s description of prototypal inheritance in Javascript, as it sounds like you’re a little fuzzy on the details.