fast-json
v3.0.0
Published
A lightning fast on the fly JSON parser
Downloads
1,927
Readme
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' }],
},
});
const fastJson = new FastJson();
// Path is a string representing a javascript object path
fastJson.on('ireland.people', (value) => {
console.log('ireland.people ->', value);
});
// Paths can be also an array of keys
fastJson.on(['spain', 'people', '1', 'name'], (value) => {
console.log(['spain', 'people', '1', 'name'], '->', value);
});
// Wildcards can be used to match all items in object or array
fastJson.on('spain.people[*].name', (value) => {
console.log('spain.people[*].name ->', value);
});
fastJson.on('*.people[*].name', (value) => {
console.log('*.people[*].name ->', value);
});
fastJson.write(data);
// The JSON can be string or Buffer
// fastJson.write(Buffer.from(data))
fastJson.on('ireland.people[1].name', (value) => {
console.log('ireland.people[1].name ->', value);
// Once we have all we need, we can skip the rest of the JSON to improve performance.
fastJson.skip();
});
// Path separator defines the keys separator on the listeners
const fastJson = new FastJson({ pathSeparator: '/' });
// In this case it allows keys having dots by using a different separator
fastJson.on('unknown.country/people/0/name', (value) => {
console.log('unknown.country/people/0/name ->', value);
});
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
- [Feature] Allow chunked JSON.
- [Feature] Match more glob patters.
- [Feature] Add more flexibility to event listeners (on, once, off, etc).
- [Documentation] Create branch gh-pages using jsdoc.
- [Documentation] More real life testing and examples.