fast-json

fast-json

A lightning fast on the fly JSON parser able to return JSON values and structures from plain JSON as String or Buffer. It's much faster than JSON.parse() and doesn't require any extra memory allocation for the data processed.

Install

npm install fast-json

Usage

const FastJson = require('fast-json');

const data = JSON.stringify({
  ireland: {
    people: [{ name: 'Alex' }, { name: 'John' }, { name: 'Cian' }],
  },
  spain: {
    people: [{ name: 'Antonio' }, { name: 'Juan' }, { name: 'Pedro' }],
  },
  'unknown.country': {
    people: [{ name: 'Frank' }, { name: 'Paul' }],
  },
  huge_list: [1, 2, 3],
});

const fastJson = new FastJson();

fastJson.on('ireland.people', (value) => {
  console.log('ireland.people ->', value);
});

fastJson.on('spain.people[1].name', (value) => {
  console.log('spain.people[1].name ->', value);
});

// Path as Array to allow keys with dots
fastJson.on(['unknown.country', 'people', '0', 'name'], (value) => {
  console.log(['unknown.country', 'people', '0', 'name'], value);
  // Stop parsing JSON usefull when have all we need improving performance
  fastJson.skip();
});

fastJson.write(data);
// or
fastJson.write(Buffer.from(data));

Performance

JSON file citylots.json of 189MB from https://github.com/zemirco/sf-city-lots-json.

• fast-json: 0.56s / 198MB RAM
• JSON.parse: 1.8s / 640MB RAM
• jsonparse: 15.0s / 1,100MB RAM (Only reading, it wasn't able to return a value)

TODO

• [Improvement] Tolerate malformed JSONs.
• [Feature] Process wildcards in paths.
• [Documentation] Document public interface and create branch gh-pages using jsdoc.
• [Documentation] More real life testing and examples.