jitson

1.0.0 verified Fri May 01 auth: no javascript

Just-In-Time JSON.parse compiler that optimizes parsing by schema sampling. Version 1.0.0 is stable. It samples incoming JSON data and if a stable schema is detected, compiles a fast parser using turbo-json-parse. Differentiators: JIT compilation based on runtime schema analysis, supports Node.js buffers for faster parsing. Maintained by mafintosh. Release cadence is low; no recent updates.

Common errors

error TypeError: jitson is not a constructor ↓

cause Using 'new jitson()' instead of calling jitson() as a function.

fix

const parse = jitson(); // No 'new' keyword

error TypeError: parse.schema is not an object ↓

cause Accessing parse.schema before any parsing has been done.

fix

Call parse() at least once before checking parse.schema. After schema stabilization it will be an object.

error Error: Unable to compile parser - schema too complex ↓

cause The JSON schema is too complex for turbo-json-parse to compile.

fix

Simplify the JSON data structure or fall back to JSON.parse.

Warnings

gotcha jitson is not a class; do not use 'new'. ↓

fix Call jitson() directly (const parse = jitson()).

gotcha The parse function expects a string or Buffer, not a parsed object. ↓

fix Pass JSON.stringify output to parse, not JSON.parse output.

gotcha The underlying turbo-json-parse may fail for very complex or nested schemas. ↓

fix Fall back to JSON.parse manually if jitson throws.

gotcha Schema detection works best when each endpoint uses a separate jitson instance. ↓

fix Create one jitson instance per API endpoint or data source.

Install

npm install jitson

yarn add jitson

pnpm add jitson

Imports

default (jitson function)
wrong
```
const jitson = require('jitson')
```
correct
```
import jitson from 'jitson'
```
Package is ESM-only; use ESM import or dynamic import() in CommonJS.
jitson constructor
wrong
```
const parse = new jitson()
```
correct
```
const parse = jitson()
```
jitson is a factory function, not a class. Do not use 'new'.
parse function
wrong
```
parse(JSON.parse(jsonString))
```
correct
```
const obj = parse(jsonString)
```
parse expects a JSON string or Buffer, not a parsed object.
parse.schema
```
const schema = parse.schema
```
After parsing, check parse.schema to see if an optimized parser is being used (null if not).

Quickstart

Demonstrates JIT compilation: after several parses with a stable schema, parse.schema becomes non-null.

import jitson from 'jitson';

const parse = jitson({ sampleInterval: 10 });

for (let i = 0; i < 10; i++) {
  const obj = parse(JSON.stringify({ hello: 'world', number: Math.random() }));
  console.log(obj);
}

console.log('Optimized schema:', parse.schema);