Czym Jest JSON? Kompletnowe Wyjaśnienie JavaScript Object Notation
Quick Answer
JSON to tekstowy format reprezentujący ustrukturyzowane dane używając par key-value i tablic. Obsługuje sześć typów danych: string, number, boolean, null, object i array. JSON to standardowy format wymiany danych między web server i przeglądarkami. Użyj naszego darmowego JSON Formatter.
Introduction
JSON (JavaScript Object Notation) to lekki, tekstowy format wymiany danych, łatwy do czytania i pisania przez ludzi, i łatwy do parsowania i generowania przez maszyny. Mimo nazwy, JSON jest language-independent —używany przez Python, Java, Go i praktycznie każdy nowoczesny język programowania. JSON jest zdefiniowany przez RFC 8259 i jest dominującym formatem dla web API i baz NoSQL.
Step by Step
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Understand JSON syntax
JSON uses curly braces {} for objects (key-value pairs), square brackets [] for arrays (ordered lists), and colons to separate keys from values. Keys must be strings in double quotes. Values can be strings, numbers, booleans, null, objects, or arrays.
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Learn the six data types
JSON supports exactly six data types: string (in double quotes), number (no distinction between int/float), boolean (true or false), null, object ({...}), and array ([...]). JSON does not support undefined, functions, dates, or NaN.
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Recognize JSON structure
A JSON document is either an object or an array at the top level. Objects contain key-value pairs; arrays contain ordered values. Structures can be nested to any depth — an object value can be another object or array.
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Parse and generate JSON
In JavaScript, JSON.parse(string) converts a JSON string to a JavaScript object, and JSON.stringify(object) converts a JavaScript object to a JSON string. Every modern language has equivalent functions.
Examples
A simple JSON object
Input: Person with name and age
Output: {"name": "Alice", "age": 30}
JSON with nested structure
Input: User with address
Output: {"name": "Alice", "address": {"city": "NYC", "zip": "10001"}}
JSON array
Input: List of numbers
Output: [1, 2, 3, 4, 5]
Common Problems
- Using single quotes —JSON requires double quotes for all strings and keys. Single quotes are invalid.
- Trailing commas —a comma after the last item in an object or array is a syntax error in JSON.
- Comments —standard JSON does not support comments. Use JSONC or JSON5 if you need comments.
- Unquoted keys —unlike JavaScript object literals, JSON requires all keys to be in double quotes.
Tips
- JSON is language-independent despite its name —every modern language has JSON support.
- Use JSON for API requests and responses —it is the de facto standard, replacing XML.
- Validate JSON before sending it in an API request to avoid 400 errors.
- Use our JSON Formatter to beautify, validate, and minify JSON instantly in your browser.