JSON Stream Stringify

JSON Stringify as a Readable Stream with rescursive resolving of any readable streams and Promises.

Important and Breaking Changes in v3.1.0

Completely rewritten from scratch - again
Buffer argument added (Stream will not output data untill buffer size is reached - improves speed)
Dropped support for node <7.10.1 - async supporting environment now required

Main Features

Promises are rescursively resolved and the result is piped through JsonStreamStringify
Streams (Object mode) are recursively read and output as arrays
Streams (Non-Object mode) are output as a single string
Output is streamed optimally with as small chunks as possible
Cycling of cyclical structures and dags using Douglas Crockfords cycle algorithm*
Great memory management with reference release after processing and WeakMap/Set reference handling
Optimal stream pressure handling
Tested and runs on ES5**, ES2015**, ES2016 and later
Bundled as UMD and Module

* Off by default since v2
** With polyfills

Install

npm install --save json-stream-stringify

# Optional if you need polyfills
# Make sure to include these if you target NodeJS <=v6 or browsers
npm install --save @babel/polyfill @babel/runtime

Usage

Using Node v8 or later with ESM / Webpack / Browserify / Rollup

No Polyfills, TS / ESM

import { JsonStreamStringify } from 'json-stream-stringify';

Polyfilled, TS / ESM

install @babel/runtime-corejs3 and corejs@3

import { JsonStreamStringify }  from 'json-stream-stringify/polyfill';
import { JsonStreamStringify }  from 'json-stream-stringify/module.polyfill'; // force ESM

Using Node >=8 / Other ES2015 UMD/CommonJS environments

const { JsonStreamStringify } = require('json-stream-stringify'); // let module resolution decide UMD or CJS
const { JsonStreamStringify } = require('json-stream-stringify/umd'); // force UMD
const { JsonStreamStringify } = require('json-stream-stringify/cjs'); // force CJS

Using Node <=6 / Other ES5 UMD/CommonJS environments

const { JsonStreamStringify } = require('json-stream-stringify/polyfill');
const { JsonStreamStringify } = require('json-stream-stringify/umd/polyfill');
const { JsonStreamStringify } = require('json-stream-stringify/cjs/polyfill');

Note: This library is primarily written for LTS versions of NodeJS. Other environments are not tested.
Note on non-NodeJS usage: This module depends on node streams library. Any Streams3 compatible implementation should work - as long as it exports a Readable class, with instances that looks like readable streams.
Note on Polyfills: I have taken measures to minify global pollution of polyfills but this library does not load polyfills by default because the polyfills modify native object prototypes and it goes against the W3C recommendations.

API

`new JsonStreamStringify(value[, replacer[, spaces[, cycle[, bufferSize=512]]]])`

Streaming conversion of value to JSON string.

Parameters

value Any
Data to convert to JSON.
replacer Optional Function(key, value) or Array
As a function the returned value replaces the value associated with the key. Details
As an array all other keys are filtered. Details
spaces Optional String or Number
A String or Number object that's used to insert white space into the output JSON string for readability purposes. If this is a Number, it indicates the number of space characters to use as white space. If this is a String, the string is used as white space. If this parameter is not recognized as a finite number or valid string, no white space is used.
cycle Optional Boolean
true enables cycling of cyclical structures and dags.
To restore cyclical structures; use Crockfords Retrocycle method on the parsed object (not included in this module).

Returns

JsonStreamStringify object that exposes a Streams3 interface.