(function () {}) (), a correlation study of function () {} ()

(function () {}) () is called self-executing anonymous function, you can use it to create a namespace, as long as you write all your own code in this special function wrapper, then the external cannot access, unless you allow.

Note that without the outer brackets, the function () {} () functions are not self-executing, an anonymous function, but not assigned to a variable

Look at the following example:

var text = (function() {                  alert ("1");                       var a = "AA";                          }) ();          Console.log (a);    

This is a self-executing function, the alert executes, internal parameters cannot be called outside

function () {                  alert ("1");                       var a = "AA";                          } ();          Console.log (a);    

This function cannot be executed, will error, anonymous function cannot execute

But after the assignment, you can do it:

        var function () {                  alert ("1");                       var a = "AA";                          } ();          Console.log ();            

The function can execute equivalent to Var text=function () {};text ();

In addition, if the self-executing function is assigned to a variable, the result is the same as above, the value of the variable is the return value of the self-executing function, here you can take an example of the previous essay:

varText = (function(){                  varA =NULL; varb =function(){                      returnA;                  }; varpublic =function(value) {//Privileged Methods                  }; Public.prototype.setName=function(value) {a=value; return  This;                  }; Public.prototype.getName=function(){                      returnA;                  }; returnPublic//return to privileged methods          })(); Console.log (text)

The value of the text here is:

(function () {}) (), a correlation study of function () {} ()