JSON is the most popular data exchange format today, used in almost all web interfaces and configuration files. It's concise, readable, and cross-language. This tutorial starts from the basics to teach you JSON's syntax rules and common pitfalls, helping you quickly understand and write JSON correctly.
What is JSON
JSON stands for JavaScript Object Notation, a lightweight text data format. It describes structured data in a human-readable way and is natively supported by most programming languages, serving as the universal language for data transfer between frontend, backend, and services.
Basic Data Types
JSON supports six types of values: strings (enclosed in double quotes), numbers, booleans (true / false), null, objects (curly braces), and arrays (square brackets).
Note: Strings must use double quotes, not single quotes; numbers are not quoted; these are the most common points of confusion for beginners.
Objects and Arrays
An object is a collection of key-value pairs, enclosed in curly braces, where keys must be strings in double quotes, for example {"name": "Xiaoming", "age": 18}. An array is an ordered list of values, enclosed in square brackets, for example [1, 2, 3].
Objects and arrays can be nested arbitrarily to represent complex hierarchical structures, such as a user object containing an address object and a tag array.
Most Common Format Errors
Common pitfalls for beginners include: trailing commas after the last element, using single quotes, unquoted key names, mismatched braces or quotes, and including comments in JSON (standard JSON does not support comments).
These errors will cause parsing failures. When encountering an error, first locate the line number based on the prompt, then focus on checking the issues mentioned above.
Validate and Format with Tools
In practical development, beautifying messy JSON into an indented format greatly facilitates reading and debugging. Using qktools' JSON formatting tool, you can format, compress, and validate JSON with one click, with errors precisely indicating the cause.
If you need to convert JSON to a table, you can also use the JSON to CSV tool for easy viewing and processing in spreadsheet software.