Question

var hash = {     
     func1: function(){

     },
     return {         
        contains: function(key) {
        return keys[key] === true;         
     },
        add: function(key) {
             if (keys[key] !== true){
             keys[key] = true;             
         }
     }      
} 

Can anyone explain me how the return works here…
Can i call hash.contains(key)
I feel the code what i have written is wrong… mean the structure?

Answer 1

var hash = (function () {
    var keys = {};
    return {
        contains: function (key) {
            return keys[key] === true;
        },
        add: function (key) {
            if (keys[key] !== true) {
                keys[key] = true;
            }
        }
    }
})();

That is what I think you were trying to achieve. From your code I thought you were trying to create a hash object with a add and contains method for checking if keys exisist within your keys var but also making it a protected variable.

What the above code does is create a closure that contains the keys variable (an object) and returns an object with the two methods contains and add.

You can read more about closures here http://jibbering.com/faq/notes/closures/. Closures are one of the biggest reasons Javascript is as flexible as it is.