How to create a new object in JavaScript?

Question

Why is this not working??

    var sheep = function(options){
        this.options = {sizes: 100,
                        eat: 100,
                 colors: 'white', 
                 running: function () {
                     return this.sizes + this.eat;
                 }
          }
    };

    var blacksheep = new sheep({colors:'black'});       

    alert('blackcsheep color is ' + blacksheep.colors);//error undefined
    alert('blackcsheep color is ' + blacksheep.options.colors);// it return white
    alert('blackcsheep running is ' + blacksheep.running());//error

Answer 1

The syntax:

var sheep = {sizes:100, eat:100, colors:'white',running:function(){
        return this.sizes+this.eat;
        }
    };

is an object literal. It defines an instance of an object, but not the class that defines it. Therefore, there is no way to "new-up" another instance of the object.

Take a look at jQuery's extend functionality:

var blacksheep = {
}

$.extend(blacksheep, sheep, { color: black });

This will copy all the properties of sheep into blacksheep, then merge the third parameter into blacksheep, effectively achieving what you want.

Answer 2

To make another black sheep based on sheep, in this scenario you could do (using jQuery):

var blacksheep = $.extend(sheep, { color: 'black' });