how to you add to an object javascript code example

Example 1: how to add property to object in javascript

var data = {
    'PropertyA': 1,
    'PropertyB': 2,
    'PropertyC': 3
};

data["PropertyD"] = 4;

// dialog box with 4 in it
alert(data.PropertyD);
alert(data["PropertyD"]);

Example 2: js add data in object

var element = {}, cart = [];
element.id = id;
element.quantity = quantity;
cart.push(element);