A complete roadmap for JSON, from syntax fundamentals to schema validation and streaming parsers. The series starts with data types, formatting rules, escaping, and UTF-8 encoding, then moves into JSON Schema—composition, $ref, and draft differences—before covering JSON Path, JSON Pointer, JSON Patch, and JSON5. It closes with advanced topics: Ajv compilation, custom keywords, TypeScript type generation, canonical and binary formats (BSON, MessagePack, CBOR), jq querying, and streaming parsers for high-volume data.
Data serialization is the process of converting an in-memory data structure into a format that can be stored or transmitted, and deserialization is the reverse. The format is the contract between the two sides: the writer produces the bytes, and the reader parses them back into the structure. The choice of format is not a…
JSON’s syntax is deliberately small. The specification at json.org describes the entire language in a few paragraphs, and the RFC 8259 adds only the encoding details and the interoperability warnings. The smallness is the point: a parser can be written in a few hundred lines, and every language has one in its standard library. The…
The JSON specification is explicit that whitespace is insignificant. The RFC 8259 states that insignificant whitespace is allowed before or after any of the six structural characters, and the json.org grammar says whitespace can be inserted between any pair of tokens . A proper JSON consumer will not see the difference between a minified payload…
A JSON string is a sequence of Unicode characters, and the JSON text that carries it must be encoded in UTF-8 when it is exchanged between systems that are not part of a closed ecosystem. The RFC 8259 makes this requirement explicit: “JSON text exchanged between systems that are not part of a closed ecosystem…
The JSON object is the boundary between the text and the in-memory data in JavaScript. The JSON.parse() method takes a JSON string and returns the JavaScript value, and the JSON.stringify() method takes a JavaScript value and returns the JSON string . The two methods are the built-in serialization mechanism, and they are the most frequently…
JSON Schema is a declarative language for describing the structure, the constraints, and the semantics of a JSON document. It is itself written in JSON, and it is used to validate the instances, to generate the documentation, and to produce the TypeScript types. The specification is split into two parts: the Core, which defines the…
The required keyword is the assertion that certain properties must be present in an object. It is the simplest of the object-validation keywords, and it is the one that the developers most often misunderstand. The keyword takes an array of strings, and the array must contain unique values. An object instance is valid against the…
The composition keywords are the boolean algebra of JSON Schema. They let a schema combine subschemas with the logical operators—the AND, the OR, the XOR, and the NOT—and the combination is the mechanism that expresses constraints a single schema cannot. The allOf is the conjunction, the anyOf is the disjunction, the oneOf is the exclusive…
The $ref keyword is the mechanism that lets a schema reuse another schema instead of duplicating it. The value of $ref is a URI reference, and the validator resolves it against the current base URI to find the referenced schema, then applies that schema to the instance location where the $ref appears . The reference…
JSONPath is a query language for JSON, and it is to JSON what XPath is to XML. It defines a string syntax for selecting and extracting values from within a JSON document, and the query returns a nodelist—zero or more nodes that match the expression . The language was designed to cover only the essential…