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JSON

JSON (JavaScript Object Notation) is a lightweight, text-based data format that’s easy to read for both humans and machines. It was derived from JavaScript but is now language-independent, making it one of the most popular formats for data exchange between applications. Key Concepts:

What is JSON Used For?

• Storing configuration settings
• Exchanging data between web servers and browsers
• APIs (Application Programming Interfaces)
• Storing structured data in files or databases
• Mobile app data storage

JSON Data Types:

Strings: Text wrapped in double quotes

{"name": "Rachel Green"}

Numbers: Integer or floating-point

{"age": 27, "height": 5.5}

Booleans: true or false

{"isStudent": true}

null: Represents no value

{"middleName": null}

Arrays: Ordered lists of values

{
  "hobbies": ["shopping", "singing", "swimming"]
}

Objects: Collections of key-value pairs

{
  "address": {
    "street": "123 Main St",
    "city": "NYC",
    "zipCode": "10001"
  }
}

Important Rules:

• All property names must be in double quotes
• Values can be strings, numbers, objects, arrays, booleans, or null
• Commas separate elements in arrays and properties in objects
• No trailing commas allowed
• No comments allowed in JSON
• Must use UTF-8 encoding

Example

{
  "studentInfo": {
    "firstName": "Monica",
    "lastName": "Geller",
    "age": 22,
    "isEnrolled": true,
    "courses": [
      {
        "name": "Web Development",
        "code": "CS101",
        "grade": 95.5
      },
      {
        "name": "Database Design",
        "code": "CS102",
        "grade": 88.0
      }
    ],
    "contact": {
      "email": "monica.g@friends.com",
      "phone": null,
      "address": {
        "street": "456 College Ave",
        "city": "Columbia",
        "state": "NY",
        "zipCode": "13357"
      }
    }
  }
}

Dont’s with JSON

• Using single quotes instead of double quotes
• Not enclosing property names in quotes
• Adding trailing commas
• Missing closing brackets or braces
• Using undefined or functions (not allowed in JSON)
• Adding comments (not supported in JSON)

Best Practices

• Always validate JSON using a JSON validator tool
• Pay attention to proper nesting of objects and arrays
• Ensure all opening brackets/braces have matching closing ones
• Check for proper use of commas

camelCase (e.g., firstName):

• Most popular in JavaScript/JSON
• Easy to read and type
• Matches JavaScript convention

Example:

{
  "firstName": "John",
  "lastLoginDate": "2024-12-20",
  "phoneNumber": "555-0123"
}

snake_case (underscores, e.g., first_name):

• Popular in Python and SQL
• Very readable
• Clear word separation

Example:

{
  "first_name": "John",
  "last_login_date": "2024-12-20",
  "phone_number": "555-0123"
}

kebab-case (hyphens, e.g., first-name):

• Common in URLs and HTML attributes
• NOT recommended for JSON
• Can cause issues because hyphen is also the subtraction operator
• Requires bracket notation to access in JavaScript

Example of why it’s problematic:

// This won't work
data.first-name  // JavaScript interprets as data.first minus name

// Must use bracket notation
data["first-name"]  // Works but less convenient

#json #dataformatVer 6.0.5