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What is JSON Format? Complete Guide to JavaScript Object Notation

File Format Guide
Reading time: 8 minutes
Author: CSVFilters Team
Published: 2025-01-20

Introduction to JSON

JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format. Despite its name suggesting a connection to JavaScript, JSON is language-independent and is used across many programming languages.

Key Features of JSON

  • Human-readable: JSON files can be easily read and understood by humans
  • Lightweight: Compared to XML, JSON is more concise and takes up less storage space
  • Language-independent: Almost all programming languages support JSON
  • Structured: Supports nested objects and array structures
  • Standardized: Based on RFC 7159 standard

JSON Syntax Rules

Basic Syntax:

  • Data exists in key-value pairs
  • Data is separated by commas
  • Objects are enclosed in curly braces
  • Arrays are enclosed in square brackets []
  • Strings must be enclosed in double quotes

JSON Data Types

Primitive Types:

  • • String
  • • Number
  • • Boolean
  • • null

Complex Types:

  • • Object
  • • Array

JSON Example

{
  "name": "John Doe",
  "age": 30,
  "isStudent": false,
  "address": {
    "city": "New York",
    "zipCode": "10001"
  },
  "hobbies": ["reading", "swimming", "programming"],
  "spouse": null
}

JSON Use Cases

Web Development:

  • • API data exchange
  • • AJAX request/response
  • • Configuration files
  • • Frontend-backend data transmission

Other Applications:

  • • Data storage
  • • Logging
  • • Mobile app development
  • • Microservices communication

JSON vs Other Formats

FeatureJSONXMLCSV
ReadabilityHighMediumHigh
File SizeSmallLargeSmall
Nested SupportYesYesNo
Parsing SpeedFastMediumFast

JSON Best Practices

Writing Guidelines:

  • Use meaningful key names
  • Maintain consistent naming conventions (e.g., camelCase)
  • Avoid overly deep nested structures
  • Use arrays and objects appropriately
  • Pay attention to data type correctness
  • Use JSON validation tools to check format

Common Mistakes

Avoid These Errors:

  • Using single quotes instead of double quotes
  • Adding comma after the last element
  • Using undefined data types
  • Key names not enclosed in quotes
  • Comments (JSON doesn't support comments)

Conclusion

JSON is an indispensable data format in modern web development. Its simplicity, readability, and widespread support make it the preferred format for data exchange. Mastering JSON syntax and best practices is an essential skill for any developer.

Related Tools:

Our website provides JSON to CSV conversion tools to help you convert between different data formats.Try it now →