Learn
Advanced Objects
Destructured Assignment

We often want to extract key-value pairs from objects and save them as variables. Take for example the following object:

const vampire = { name: 'Dracula', residence: 'Transylvania', preferences: { day: 'stay inside', night: 'satisfy appetite' } };

If we wanted to extract the residence property as a variable, we could using the following code:

const residence = vampire.residence; console.log(residence); // Prints 'Transylvania'

However, we can also take advantage of a destructuring technique called destructured assignment to save ourselves some keystrokes. In destructured assignment we create a variable with the name of an object’s key that is wrapped in curly braces { } and assign to it the object. Take a look at the example below:

const { residence } = vampire; console.log(residence); // Prints 'Transylvania'

Look back at the vampire object’s properties in the first code example. Then, in the example above, we declare a new variable residence that extracts the value of the residence property of vampire. When we log the value of residence to the console, 'Transylvania' is printed.

We can even use destructured assignment to grab nested properties of an object:

const { day } = vampire.preferences; console.log(day); // Prints 'stay inside'

Instructions

1.

Use destructured assignment to create a const variable named functionality that extracts the functionality property of robot.

If you need a reminder on how to use destructured assignment, review the example in the narrative or check the hint.

2.

Since functionality is referencing robot.functionality we can call the methods available to robot.functionality simply through functionality.

Take advantage of this shortcut and call the .beep() method on functionality.

Folder Icon

Take this course for free

Already have an account?