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JavaScript Object Notation (JSON)

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descriptionJavaScript Object Notation (JSON)
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Overview​

JSON, short for JavaScript Object Notation, is a text-based format for representing structured data.

It matters because it has become one of the default formats for APIs, configuration files, event payloads, and machine-to-machine data exchange.

What JSON Is Good At​

JSON is designed to be simple for humans to read and straightforward for software to parse.

It represents data using a small set of building blocks:

  • objects made of key-value pairs
  • arrays of ordered values
  • strings
  • numbers
  • booleans
  • null

That simplicity is one reason it shows up so often in api and rest-api work.

Common Uses​

JSON is commonly used for:

  • API requests and responses
  • application configuration
  • structured logs and messages
  • export and import payloads
  • data exchanged between frontend and backend code

It is especially common in JavaScript-heavy stacks, but it is not limited to js applications.

JSON vs JavaScript Objects​

JSON came from the JavaScript ecosystem, but JSON is not the same thing as a general JavaScript object literal.

  • JSON has stricter syntax rules.
  • Property names must use double quotes.
  • Trailing commas are not allowed.
  • Functions and comments are not part of the format.

That distinction matters because files that look close enough to JavaScript may still be invalid JSON.

JSON vs YAML​

JSON is often compared with yaml.

  • JSON is more explicit and usually easier for machines to validate consistently.
  • YAML is often easier for humans to scan in configuration files.

Teams often choose JSON when strictness and interoperability matter more than authoring comfort.

Practical Caveats​

JSON is widely supported, but it has limits.

  • It does not support comments in the standard format.
  • Large documents can become hard to read manually.
  • It does not preserve richer data types such as dates by itself.
  • Schema validation is separate from the base format.

That is why teams often pair JSON with conventions, schemas, or typed models.

Frequently Asked Questions​

Is JSON only for JavaScript?​

No. It is language-neutral and widely used across many ecosystems.

Can JSON contain comments?​

Not in the standard format defined by the official specifications.

Is JSON a markup language?​

Not usually. It is a data serialization format rather than a document markup format like html or xml.

Resources​