JavaScript’s core—most often used and most fundamental—data type is the Object data type. JavaScript has one complex data type, the Object data type, and it has five simple data types: Number, String, Boolean, Undefined, and Null. Note that these simple (primitive) data types are immutable (cannot be changed), while objects are mutable (can be changed).

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What is an Object
An object is an unordered list of primitive data types (and sometimes reference data types) that is stored as a series of name-value pairs. Each item in the list is called a property (functions are called methods).

Consider this simple object:

var myFirstObject = {firstName: “Richard”, favoriteAuthor: “Conrad”};

Think of an object as a list that contains items, and each item (a property or a method) in the list is stored by a name-value pair. The property names in the example above are firstName and favoriteAuthor. And the values are “Richard” and “Conrad.”

Property names can be a string or a number, but if the property name is a number, it has to be accessed with the bracket notation. More on bracket notation later. Here is another example of objects with numbers as the property name:

var ageGroup = {30: “Children”, 100:”Very Old”};
console.log(ageGroup.30) // This will throw an error
// This is how you will access the value of the property 30, to get value “Children”
console.log(ageGroup[“30”]); … Continue reading JavaScript Objects in Detail