@lezer/json

What is @lezer/json?

@lezer/json is a parser for JSON that is part of the Lezer parser system. It provides a way to parse JSON data into a syntax tree, which can then be used for various purposes such as syntax highlighting, code analysis, and transformation.

What are @lezer/json's main functionalities?

Parsing JSON

This feature allows you to parse a JSON string into a syntax tree. The syntax tree can then be used for further analysis or transformation.

const {parser} = require('@lezer/json');
const input = '{"key": "value"}';
const tree = parser.parse(input);
console.log(tree.toString());

Syntax Tree Traversal

This feature demonstrates how to traverse the syntax tree generated by the parser. You can visit each node and perform operations based on the node type.

const {parser} = require('@lezer/json');
const input = '{"key": "value"}';
const tree = parser.parse(input);

function traverse(node) {
  console.log(node.type.name);
  for (let child of node.children) {
    traverse(child);
  }
}

traverse(tree.topNode);

Error Handling

This feature shows how to handle errors during parsing. If the input JSON is malformed, the parser will throw an error which can be caught and handled appropriately.

const {parser} = require('@lezer/json');
const input = '{"key": "value"'; // Missing closing brace
try {
  const tree = parser.parse(input);
  console.log(tree.toString());
} catch (e) {
  console.error('Parsing error:', e.message);
}

Other packages similar to @lezer/json

json5

json5 is a JSON parser that allows for more human-friendly JSON syntax, including comments and trailing commas. Unlike @lezer/json, which focuses on creating a syntax tree for analysis, json5 is more about providing a flexible JSON parsing experience.

jsonlint

jsonlint is a JSON parser and validator. It checks JSON for syntax errors and can format JSON data. While @lezer/json provides a syntax tree for further manipulation, jsonlint is more focused on validation and formatting.

fast-json-parse

fast-json-parse is a fast JSON parser that aims to provide high performance. It is less feature-rich compared to @lezer/json, which provides a detailed syntax tree for further analysis and manipulation.

README

@lezer/json

This is a JSON grammar for the lezer parser system.

Reference:

• https://www.json.org/json-en.html
• https://tools.ietf.org/html/rfc8259 (The latest IETF RFC – contains the latest full spec)

Changelog

0.16.0 (2022-04-20)

Breaking changes

Move to 0.16 serialized parser format.

New features

The parser now includes syntax highlighting information in its node types.