private method in an javascript object

Question

I've an object looks like this:

var obj ={

  property : '',
  myfunction1 : function(parameter){
     //do stuff here
  }
}

I need to set some private properties and functions, which can not be accessed/seen from outside of the object. It is not working with var property:, or var myFunction1

Next question is, if I call a function within or outside the object, I always have to do this with obj.myfunction(). I would like to asign "this" to a variable. Like self : this. and call inside the object my functions and variables with self.property and self.myfunction.

How? :)

score 1 · Answer 1 · edited Oct 17 '14 at 09:16

1

There are many ways to do this. In short: If dou define a function inside another function, your inner function will be private, as long as you will not provide any reference to if.

(function obj(){
    var privateMethod = function() {};
    var publicMethod = function() {
        privateMethod();
        ...
    };

    return {
        pubMethod: publicMethod
    }
}());

edited Oct 17 '14 at 09:16

sampathsris

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answered Oct 17 '14 at 09:08

Beri

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This link could help you later on: http://stackoverflow.com/questions/55611/javascript-private-methods – Beri Oct 17 '14 at 09:09

score 0 · Answer 2 · answered Oct 17 '14 at 09:09

var obj = (function() {
  var privateProperty;
  var privateFunction = function(value) {
    if (value === void 0) {
      return privateProperty;
    } else {
      privateProperty = value;
    }
  };
  var publicMethod = function(value) {
    return privateFunction(value);
  }

  return {
    getPrivateProperty: function() {
      return privateFunction();
    },
    setPrivateProperty: function(value) {
      privateFunction(value);
    }
  }
})();

obj.setPrivateProperty(3);
console.log(obj.getPrivateProperty());
// => 3
console.log(obj.privateProperty);
// => undefined
obj.privateFunction();
// => TypeError: undefined is not a function

score 0 · Answer 3 · answered Oct 17 '14 at 09:09

Use closures. JavaScript has function scope, so you have to use a function.

var obj = function () {
    var privateVariable = "test";
    function privateFunction() {
        return privateVariable;
    }

    return {
        publicFunction: function() { return privateFunction(); }
    };
}();

private method in an javascript object

3 Answers3