JS Closed Package

JS Closure website: http://www.cnblogs.com/qieguo/p/5457040.html

What is JS closure

A function that has access to a variable within the scope of another function is a closure.

Here the F function accesses the variable n in constructor A, thus forming a closure. look at the code again .

  1  function A () {  2   var n = 0;   3   function f () {  4   n++;   5   Console.log (n);   6  }   7   return F;   8  }   9  10  var C = A ();   11  c ();  Console Output 1  12  C (); Console Output 2 

See how it's done:

var c = couter (), this sentence couter () returns the function Inc, which is equivalent to var c = f;

C (), this sentence is equivalent to f (); Note that the function name is just an identifier (a pointer to a function) and () is the execution function.

The following three sentences are translated: var C = f;  f (); f (); Is it different from the first code? No.

Why do you write like that?

We know that every function of JS is a small black house, it can get outside information, but the outside world can't directly see the content. Put the variable n into the small black room, in addition to the F function, there is no other way to contact the variable n, and in the function a outside the definition of the same name variable n is not affected, this is called enhanced "encapsulation."

The reason to return the function ID F with return is because the F function cannot be called directly outside the A function, so return f is associated with the outside.

The use of JS closures

http://blog.csdn.net/sunlylorn/article/details/6534610

Let's take a look at the use of closures. In fact, we can do a lot of things by using closures. such as simulating object-oriented code style, more elegant, more concise expression of code, in some ways to improve the efficiency of code execution.

1 anonymous self-executing functions

2 Cache

3 Implementing Encapsulation

Another important use of the 4 closures is to implement object-oriented objects, which provide a template mechanism for the class, and the traditional object language

JS Closed Package