JSON

Question 1

What is JSON?

Answer 1

JSON (JavaScript Object Notation) is a text-based data format that follows JavaScript object syntax. It represents structured data as a string.

Question 2

What are serialization and deserialization?

Answer 2

Serialization converts an object/array to a stream of bytes to store or send over a network.

Deserialization converts a stream of bytes to an object/array that can be used in a program.

Question 3

Why are serialization and deserialization useful?

Answer 3

It allows objects to be saved, transferred, and recreated.

Question 4

How do you serialize a data structure into a JSON string using JavaScript?

Answer 4

The .stringify() method on the JSON object.

Question 5

How do you de-serialize a JSON string into a data structure using JavaScript?

Answer 5

The .parse() method of the JSON object.

Question 6

How do you store data in localStorage?

Answer 6

By calling the .setItem() method of the localStorage object with two arguments: a string for the key and a JSON string for the value.

Question 7

How do you retrieve data from localStorage?

Answer 7

By calling the .getItem() method of the localStorage property with one argument: the string of the key.

Question 8

What data type can localStorage save in the browser?

Answer 8

The string data type.

Question 9

When does the ‘beforeunload’ event fire on the window object?

Answer 9

Before the tab is closed or refreshed. Anything that would cause the application to reload or close.