Lesson 12 - Object Properties in JavaScript - Data Descriptors

In the previous lesson, Object Properties in JavaScript, we explained more about JavaScript object properties. We can add them to already existing objects, delete them, iterate through all the properties of an object, or ask whether the object has a certain property. But that's far from everything. Today, we're going to look at property descriptors.

Descriptors

Each object property has its descriptor. It describes how it can be handled. For example, we can make properties read-only or even simulate a property that the object actually doesn't have. The descriptors are divided into two groups:

• data descriptors modify the behavior of properties carrying data. Such a property can be, for example, name of a human object.
• accessor descriptors allow us to use callback functions to fully control access to properties. For example, we can create properties that do not return the stored data directly but calculate them, see further.

We can modify the behavior of any object property using either the data or the accessor descriptor (but we can't use both descriptors on the same property).

Let's now show what the descriptors allow us to do on a simple table:

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