Last updated 2022-11-05 03:50:45

What Is Json?

Table of contents


JavaScript Object Notation (JSON) is a format derived from JavaScript that only uses text to store and transmit data. It helps represent structured data in a text format, which is done through the pairing of values and labels known as keys. A major benefit of JSON is its easy-to-use format for storing and transmitting data. The JSON format is typically used when data is sent from a server to a webpage.

Use Case and Examples

Here is an example of student data held in JSON format

01: { 02: "employees":[ 03: { 04: "name":"John Doe", 05: "age":12, 06: "score":5.5 07: }, 08: { 09: "name":"Jane Doe", 10: "age":18, 11: "score":2.5 12: } 13: ] 14: }

Now there are different data types that JSON can store and these are:

  • String: JSON can store any form of alphanumeric text, like names or even blog posts.
  • Number: is any form of integer or float(decimal number).
  • Object: sometimes you want to have a block of data that needs to be associated with a key, so say the key is an employee's name, and you have many values to attribute to him/her you will use an object, just like the example above.
  • Array: is suitable for representing a list of items, it could be a list of fruits, a list of countries, etc.
  • Boolean: is used to represent a true or false state. For example, you can have this {"closed":true}.
  • null: is used to represent emptiness.

To be clear JSON is a key-value pair kind of exchange format, meaning on the left you have a label known as the key and to the right is the value, different data types can be used for the value but the key always has to be a string. You can get around using a number as a string though by just wrapping double quotes around it ie: {"1":"Usain Bolt"}. Also, single quotes can not be used in JSON to wrap around strings, only double quotes.


In short, JSON provides an easy-to-use format to store data in a key-value pair [→] format. In the past, a more verbose data exchange medium was used known as XML but JSON replaced it given it's a lot less verbose which means less unrelated data needs to be transferred over a network for example.

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