Calling private method in javascript object

Question

here is my javascript:

function namespace(nameSpaceString){
    var parts = nameSpaceString.split(".");
    var parent = window;
    var currentParent = '';

    for(var i=0, len=parts.length; i<len;i++){
        currentParent = parts[i];
        parent[currentParent] = parent[currentParent] || {};
        parent = parent[currentParent];
    }

    return parent;
}
abc = namespace('ns.abc');

abc.common = function(){
    var arr = [];

    setArr = function(v){
        if(v){
            arr.push(v);
        }
    }
    getArr = function(){
        return arr;
    }

    registerArr = function(ns){
        if(ns){
            for(var obj in ns){
                if(obj.hasOwnProperty(getName)){
                    setArr(obj.getName());
                }
            }
        }
    }
    return{
      setArr : setArr,
      getArr : getArr,
      registerArr : registerArr
   }
}

abc.form = function() {
var salutation = "Hi";
var name = '';

getSalutation = function(){
    return salutation;
}
getName = function(){
    return name;
}
setSalutation = function(s){
    salutation = s;
}
setName = function(n){
    name = n;
}

return{
    getSalutation:getSalutation,
    setSalutation:setSalutation,
    getName : getName,
    setName : setName
    }
}

persons = namespace('ns.abc.persons');
persons.Dave = new abc.form();

persons.Dave.setName("Dave");

persons.Mitchell = new abc.form();

persons.Mitchell.setName('Mitchell');
persons.Mitchell.setSalutation('Howdy');

alert(persons.Mitchell.getSalutation()+":"+persons.Mitchell.getName());
commonObj = new abc.common();

commonObj.registerArr(persons);
alert("Registration:"+commonObj.getArr())

commonObj.setArr(persons.Dave.getName());
commonObj.setArr(persons.Mitchell.getName());
alert("Setter Methods:"+commonObj.getArr());

Here the Arr in Common when set by setter method works fine. But when I try to achieve the same by calling setter method form another member function -"registerArr" of the same object, it returns nothing.

How can I use setter method from within another member function?

your for.. in loop is wrong! Work that out and your problem will be solved. (Use normal iteration.. no need to complicate things). Also, you shouldn't be creating so many globals! use 'var' its your friend! — GAgnew
– GAgnew, Commented Aug 10, 2011 at 20:16

SLaks · Accepted Answer · 2011-08-10 19:57:56Z

2

You need to declare the variables holding the functions using var.

Since you aren't declaring them, the variables become globals.

Therefore, registerArr will always use the functions from the last instance created, since that's what's in the global variables.

Also, you're misusing the for... in loop.
obj iterates over the keys of every property in the object.
To iterate over an array, use a normal for loop.

answered Aug 10, 2011 at 19:57

SLaks

891k182 gold badges1.9k silver badges2k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Dhwanit Over a year ago

declaring the properties using var works fine. However if I were to use "this" inside registerArr i.e. this.setArr(), that will still point to the locally declared method of that particular instance of common object object, right?

gilly3 · Accepted Answer · 2011-08-10 20:44:20Z

0

There are two issues with your for..in loop:

obj refers to the key not the value. Get the value by using ns[obj].
The argument for .hasOwnProperty() needs to be a string. Add quotes.

Here is the corrected loop:

for (var obj in ns) {
    if (ns[obj].hasOwnProperty("getName")) {
        setArr(ns[obj].getName());
    }
}

Here is a working jsFiddle: http://jsfiddle.net/UdyYv/10/

Besides that, there were some other problems in your jsFiddle that caused it to fail, throwing errors when run. You needed to declare namespace.abc and namespace.abc.person.

This turned out to be a red herring. Because you are instantiating instances of abc.common using the new keyword, abc.common needs to specify methods, rather than returning an object. Remove the return statement and replace with this:

this.setArr = setArr; this.getArr = getArr; this.registerArr = registerArr;

If you don't want to use this approach, than you should not instantiate it using the new keyword. Instead just call it:

commonObj = abc.common();

edited Aug 10, 2011 at 20:44

answered Aug 10, 2011 at 20:00

gilly3

92.6k26 gold badges148 silver badges179 bronze badges

2 Comments

Dhwanit Over a year ago

how can I get more than one instances of the same object if I dont declare using the key word new? Look at the persons object, it follows the same return pattern as common object and it works fine for Dave and Mitchell objects

gilly3 Over a year ago

@user - Your function is not returning a reference to a singleton object, it's returning an object literal. Every time you call abc.common() you get a new unique object. As for the new keyword, I see that it does indeed still work with it, which surprises me a little. It turns out the real issue with your code is the two problems in your for..in loop, which I added to my answer.

Collectives™ on Stack Overflow

Calling private method in javascript object

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related