add(1)(2)(3).total === 6 - Has anyone else seen self returning functions used like this? [closed]

Question

The following code works, and while I understand why it works, I haven't seen it anywhere. I assume this is because all the other design patterns are much better.

I would still have expected to see the example as a cautionary tale along the line but I have not.

Sure, it is awful, especially with the example below which I chose because it is clear what it does but:

What is this pattern called?

Is it commonly used?

Are there any legitimate projects that use this pattern?

var add = function container (val) {

  addFunc = function f (val, undefined) {
  addFunc.total += val;
  return addFunc;
  };

addFunc.total = 0;

return addFunc(val);
};

alert(add(1)(2)(3).total);
alert(add(1)(2)(33).total);

Edit: Variable name change so that the code works in IE.

Answer 1

Technically, this could be considered chaining or encapsulation.

You chain when you can perform a set of operations indefinitely off an original function. jQuery uses a form of this when you can chain calls to set properties and attributes off an original selector. In this situation, the creator wanted to be able to chain calls to add without having to retype the function name. Not the cleanest of ideas, but valid.

Also, since the actual body of the code is never exposed to the caller, this could also be considered encapsulation since the addFunc method is not exposed to the outside scope.