What is this pattern's name / purpose? [duplicate]

Question

I didn't find a post asking for a pattern similar to this one, sorry if I missed it.

Anyway, I'm repeateadly seeing this pattern in many jQuery plugins or scripts:

(function () {
  ...........
}());

What's its purpose? Does it have a name?

Thanks!

Answer 1

It's also known as an Immediately Invoked Function Expression

Ben Alman has a good article covering IIFE usage, and why "self-executing anonymous function" isn't the best terminology:

One of the most advantageous side effects of Immediately-Invoked Function Expressions is that, because this unnamed, or anonymous, function expression is invoked immediately, without using an identifier, a closure can be used without polluting the current scope.

[... T]the term “self-executing” is somewhat misleading, because it’s not the function that’s executing itself, even though the function is being executed. Also, “anonymous” is unnecessarily specific, since an Immediately Invoked Function Expression can be either anonymous or named. And as for my preferring “invoked” over “executed,” it’s a simple matter of alliteration; I think “IIFE” looks and sounds nicer than “IEFE.”

Answer 2

It's a an immediately invoked function expression (Fiddle):

(function () {
  alert("pee");
}());