JSON Overview

JSON Overview

1. What is it?

   • Stands for JavaScript Object Notation.
   • Lightweight data interchange format
   • Self-describing and easy to understand for humans.
   • Example
     • “movie”: [ { “season”: “01”, “language”: “english”, “episode”: “second”, “director”: “Robert Anderson” } ]
   • Has been used since 2001.

2. Data Interface

   • Once JSON data is fetched from an API or local JSON file, HTML and even CSS can be used to display the data in a simple, readable table with rows and columns.

3. Data structures

   • In JSON, data is represented in name/value pairs separated by a comma. The curly bracket contains the object and is separated from the name by a colon. Square brackets hold arrays, and a comma separates the array from values.
   • Most data used in JSON ends up being encapsulated in a JSON object. Key-value pairs have a colon between them as in "key" : "value" . Each key-value pair is separated by a comma, so the middle of a JSON lists as follows: "key" : "value", "key" : "value", "key": "value"

4. Data specifications

   • Name/value: A name/value pair consists of a field name (in double quotes), followed by a colon, followed by a value:
     • eg. "firstName":"John"
   • Objects: JSON objects are written inside curly braces and objects can contain multiple name/value pairs.
     • eg. {"firstName":"John", "lastName":"Doe"}
   • Arrays: an array can contain objects.
     • eg. "employees":[ {"firstName":"John", "lastName":"Doe"}, {"firstName":"Anna", "lastName":"Smith"}, {"firstName":"Peter", "lastName":"Jones"} ]
   • Constraints
     • A value in JSON must be: a string, a number, an object, an array, a boolean, or null.
     • String values must be written with double quotes.
   • Numbers: Must be an integer or a floating point in JSON.
     • e.g.{"age":50}
   • Booleans: Values can be true/false in JSON.
     • {"request":true}
   • Null: Values can be null in JSON.
     • {"phonenumber":null}