Chapter 6 Sets code does not work

[saidbakr]

I have the following code that I have get till page 94 of the first edition:

function Set() {
    var items = {};
    
    this.has = function(value) {
        return items.hasOwnProperty(value);
    }
    this.add = function(value){
        if(!this.has(value)){
            items[value] = value;
            return true;
        }
        return false;
    }    
}

var set = new Set();
set.add(1);
set.add(5);
set.add(10);
console.log(set.items); //undefined

The console.log outputs undefined. I'm using Google Chrome Version 62.0.3202.75 64 bit on Ubuntu linux and my files structure is two files:

1. index.html
2. js.js

[loiane]

Hi @saidbakr, because it was used functions, the items is a private variable, so it cannot be accessed directly. To console.log the items, you need to add the getItems function as demonstrated here: https://github.com/loiane/javascript-datastructures-algorithms/blob/first-edition/chapter06/01-Set.js#L76

[saidbakr]

@loiane
Hi,
As I know from OOP. items is a public property of the class Set and items has global scope in its class. Hence, any instance object of this class should inherit its public property items and it should be public too. i.e at least console.log(set.items) returns null but not undefined.
I think the code in the book is correct as it is. The question is: Why it does not work in my browser?

[loiane]

Hi @saidbakr, this code is not really OO, is uses closures from JavaScript. In this particular case the var items is private to the function scope only.
If you use the class syntax from ES6 or the prototype from JS, then the items variable will be public.