JSON Structure Explained

What is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based data format designed for data interchange between systems. Created by Douglas Crockford in the early 2000s, JSON has become the de facto standard for web APIs, configuration files, and data storage.

Despite its name, JSON is language-independent and supported by virtually every modern programming language including JavaScript, Python, Java, C#, PHP, Ruby, Go, and Rust.

Basic JSON Structure

JSON data is built from two primary structures:

{
  "name": "Alice",
  "age": 30,
  "active": true
}

[
  "apple",
  "banana",
  "cherry"
]

JSON Data Types

JSON supports six fundamental data types:

JSON Syntax Rules

• ✓
  Double Quotes Only: Keys and string values must use double quotes, not single
• ✓
  No Trailing Commas: Last item in object/array cannot have trailing comma
• ✓
  UTF-8 Encoding: Standard encoding, supports Unicode characters
• ✓
  No Comments: Standard JSON doesn't support comments (use JSON5 for comments)
• ✓
  Case Sensitive: Keys are case-sensitive: "Name" ≠ "name"

Nested JSON Structures

Real-world JSON often contains deeply nested objects and arrays:

{
  "user": {
    "id": 12345,
    "profile": {
      "name": "Alice Johnson",
      "email": "alice@example.com",
      "preferences": {
        "theme": "dark",
        "notifications": true
      }
    },
    "roles": [
      {"id": 1, "name": "admin", "permissions": ["read", "write", "delete"]},
      {"id": 2, "name": "editor", "permissions": ["read", "write"]}
    ]
  }
}

When converting nested JSON to flat formats like CSV, you'll need flattening strategies.

Common JSON Mistakes

Validating JSON

Always validate JSON before processing to catch syntax errors:

try {
  const data = JSON.parse(jsonString);
  console.log("Valid JSON:", data);
} catch (error) {
  console.error("Invalid JSON:", error.message);
}