JSON

JSON (JavaScript Object Notation) is a lightweight data interchange format that has become the de facto standard for web APIs and configuration files. Its simplicity and language independence make it ubiquitous in modern software.

Format

{
  "name": "Alice",
  "age": 30,
  "email": "alice@example.com",
  "roles": ["admin", "user"],
  "address": {
    "city": "Sydney",
    "country": "Australia"
  },
  "active": true,
  "metadata": null
}

Data Types

Type	Example
String	"hello"
Number	42, 3.14, -17
Boolean	true, false
Null	null
Array	[1, 2, 3]
Object	{"key": "value"}

Common Operations

JavaScript

// Parse JSON string
const data = JSON.parse('{"name": "Alice"}');

// Stringify object
const json = JSON.stringify({ name: 'Alice' }, null, 2);

// Fetch API returns JSON
const response = await fetch('/api/users');
const users = await response.json();

Schema Validation

// Using Zod
import { z } from 'zod';

const UserSchema = z.object({
  name: z.string(),
  email: z.string().email(),
  age: z.number().optional(),
});

const user = UserSchema.parse(jsonData);

JSON vs Alternatives

Format	Best For
JSON	APIs, config, general interchange
CSV	Tabular data, spreadsheet import
YAML	Human-edited configuration
XML	Legacy systems, SOAP
Parquet	Analytics, columnar queries
MessagePack	Binary JSON, performance

What We Like

• Simplicity: Easy to read, write, and understand
• Universal: Every language has JSON support
• Web native: JavaScript parses it natively
• Self-describing: Schema is implicit in structure
• Tooling: Excellent editor and debugger support

What We Don't Like

• No comments: Unlike YAML or JSON5
• Verbosity: Repeated keys, lots of quotes
• No dates: Must use strings or numbers
• Limited types: No distinction between int/float
• Large files: Less efficient than binary formats

Best Practices

1. Validate input: Never trust external JSON (use Zod, Joi, ajv)
2. Use ISO 8601 for dates: "2024-01-15T10:30:00Z"
3. Keep it flat: Deep nesting complicates parsing
4. Consider JSON:API: Standard for API responses
5. Compress for transfer: gzip significantly reduces size

Related Tools

• JSONPath: Query JSON like XPath queries XML
• jq: Command-line JSON processor
• JSON Schema: Formal schema definition
• JSON5: JSON with comments and trailing commas