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What is JSON?

JSON stands for JavaScript Object Notation. It is a lightweight data-interchange format that is easy for humans to read and write, and easy for machines to parse and generate.

Illustration of What is JSON?
Illustration of What is JSON?

💡 Key Point

JSON is language-independent but uses conventions familiar to JavaScript programmers.

JSON is primarily used to transmit data between a server and a web application as text. It represents data as key-value pairs and ordered lists.

JSON Data Types
TypeDescription
ObjectUnordered set of key-value pairs enclosed in curly braces {"key": "value"}
ArrayOrdered list of values enclosed in square brackets ["item1", "item2"]
StringText enclosed in double quotes "Hello"
NumberInteger or floating-point numbers 42, 3.14
Booleantrue or false
nullRepresents empty or no value null

⚠️ Important Restrictions

JSON keys must be double-quoted strings. Single quotes or unquoted keys are invalid. Also, functions, dates, and undefined are not valid JSON values.

📌 Deep Dive: Simple JSON Example

JAVASCRIPT
{
  "name": "Alice",
  "age": 30,
  "isStudent": false,
  "hobbies": ["reading", "swimming"],
  "address": {
    "city": "Wonderland",
    "zip": "12345"
  }
}

JSON strings are often exchanged between systems. In JavaScript, you can convert JSON text into a JavaScript object using JSON.parse(), and convert objects back to JSON text with JSON.stringify().

💡 Why JSON?

Compared to XML, JSON is more compact and easier to work with in JavaScript environments, making it the preferred format for web APIs and configuration files.

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