JSON Syntax

📋 JSON Syntax Rules

JSON syntax is derived from JavaScript object notation. It follows specific rules that make it easy to read and parse.


{
  "name": "Alice",
  "age": 25,
  "active": true
}

Key Rules:

✓ Keys must be strings in double quotes

✓ Values can be strings, numbers, booleans, etc.

✓ Use commas to separate key-value pairs

Essential Syntax Rules

""

Double Quotes

Strings must use double quotes

"name": "John"

{}

Curly Braces

Objects are wrapped in curly braces

{"key": "value"}

[]

Square Brackets

Arrays use square brackets

["apple", "banana"]

,

Commas

Separate items with commas

"a": 1, "b": 2

🔹 Valid JSON Structure

Here's a properly formatted JSON object:

{
  "student": {
    "id": 12345,
    "name": "Sarah Johnson",
    "email": "[email protected]",
    "enrolled": true,
    "gpa": 3.85,
    "courses": [
      "Mathematics",
      "Physics",
      "Computer Science"
    ],
    "address": {
      "street": "456 Oak Avenue",
      "city": "Boston",
      "zipCode": "02101"
    }
  }
}

This JSON is valid because:

✓ All strings use double quotes

✓ Objects use curly braces {}

✓ Arrays use square brackets []

✓ Commas separate all items

✓ No trailing commas

🔹 Common Syntax Errors

Avoid these common mistakes:

❌ Wrong - Single Quotes

// INVALID
{
  'name': 'John',
  'age': 30
}

✅ Correct - Double Quotes

{
  "name": "John",
  "age": 30
}

❌ Wrong - Trailing Comma

// INVALID
{
  "name": "John",
  "age": 30,
}

✅ Correct - No Trailing Comma

{
  "name": "John",
  "age": 30
}

🔹 JSON Value Types

JSON supports these data types:

{
  "string": "Hello World",
  "number": 42,
  "boolean": true,
  "null_value": null,
  "object": {
    "nested": "value"
  },
  "array": [1, 2, 3, 4, 5]
}

Supported Types:

String: Text in double quotes
Number: Integer or decimal
Boolean: true or false
null: Represents empty value
Object: Collection of key-value pairs
Array: Ordered list of values

🔹 Nested JSON Example

JSON can contain nested objects and arrays:

{
  "company": "Tech Corp",
  "employees": [
    {
      "id": 1,
      "name": "Alice Smith",
      "department": "Engineering",
      "skills": ["JavaScript", "Python", "React"],
      "contact": {
        "email": "[email protected]",
        "phone": "+1-555-0123"
      }
    },
    {
      "id": 2,
      "name": "Bob Wilson",
      "department": "Design",
      "skills": ["Photoshop", "Figma", "CSS"],
      "contact": {
        "email": "[email protected]",
        "phone": "+1-555-0124"
      }
    }
  ]
}