JSON Cheat Sheet

{
  "key": "value"
}

// JSON does NOT support comments
// Use JSDoc or remove before parsing

// Keys MUST be quoted strings
{
  "name": "valid",
  name: "invalid"
}

{
  "name": "John",
  "city": "New York"
}

{
  "age": 30,
  "price": 19.99,
  "negative": -5,
  "scientific": 1.2e+3
}

{
  "isActive": true,
  "isDeleted": false
}

{
  "value": null
}

// JSON does NOT support undefined
// Use null instead

{
  "fruits": ["apple", "banana", "orange"]
}

{
  "mixed": [1, "two", true, null]
}

{
  "matrix": [
    [1, 2, 3],
    [4, 5, 6]
  ]
}

{
  "users": [
    {"name": "Alice", "age": 25},
    {"name": "Bob", "age": 30}
  ]
}

{
  "items": []
}

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

{
  "user": {
    "profile": {
      "name": "John",
      "address": {
        "city": "NYC"
      }
    }
  }
}

{
  "config": {}
}

{
  "person": {
    "name": "John",
    "hobbies": ["reading", "coding"]
  }
}

{
  "quote": "\"Hello\"",
  "backslash": "\\",
  "newline": "Line 1\nLine 2",
  "tab": "Col1\tCol2"
}

{
  "unicode": "\u0041",
  "emoji": "\uD83D\uDE00"
}

\" \\ \/ \b \f \n \r \t \uXXXX

{
  "name": "John",
  "age": 30,
  "hobbies": [
    "reading",
    "coding"
  ]
}

{"name":"John","age":30,"hobbies":["reading","coding"]}

// Invalid:
{
  "a": 1,
  "b": 2,
}

// Valid:
{
  "a": 1,
  "b": 2
}

{
  "status": "success",
  "data": {
    "id": 1,
    "name": "Product"
  },
  "message": "Retrieved"
}

{
  "app": {
    "name": "MyApp",
    "version": "1.0.0",
    "port": 3000
  }
}

{
  "name": "my-package",
  "version": "1.0.0",
  "dependencies": {
    "express": "^4.18.0"
  }
}

{
  "error": {
    "code": 404,
    "message": "Not Found",
    "details": []
  }
}

// Cannot include comments in JSON
// Remove before parsing

// Cannot include functions
{
  "invalid": function() {}
}

// No native date type
{
  "date": "2024-01-01T00:00:00Z"
}

// Use null instead
{
  "value": null
}

// Last item cannot have comma
{
  "a": 1  // OK
}