Question

How can I create a function that can’t be called from outside?

var obj = {
    function1: function(){
        alert("function1");
    },
    function2: function(){
        alert("function2...");
        obj.function1();
    }
};
// so how to make this function unaccessible 
obj.function1();
// and you could only call this function
obj.function2();

Answer 1

You may want to consider using the Yahoo Module Pattern. This is a singleton pattern, and the methods are not really static, but it may be what you are looking for:

var obj = (function () {

   //"private" variables:
   var myPrivateVar = "I can be accessed only from within obj.";

   //"private" method:
   var myPrivateMethod = function () {
      console.log("I can be accessed only from within obj");
   };

   return {
      myPublicVar: "I'm accessible as obj.myPublicVar",

      myPublicMethod: function () {
         console.log("I'm accessible as obj.myPublicMethod");

         //Within obj, I can access "private" vars and methods:
         console.log(myPrivateVar);
         console.log(myPrivateMethod());
      }
   };
})();

You define your private members where myPrivateVar and myPrivateMethod are defined, and your public members where myPublicVar and myPublicMethod are defined.

You can simply access the public methods and properties as follows:

obj.myPublicMethod();    // Works
obj.myPublicVar;         // Works
obj.myPrivateMethod();   // Doesn't work - private
obj.myPrivateVar;        // Doesn't work - private