JSON.Stringify as a readable stream
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JSON Stringify as a Readable Stream with rescursive resolving of any readable streams and Promises.
- 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
- 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
``bash
npm install --save json-stream-stringify
Usage
Using Node v8 or later with ESM / Webpack / Browserify / Rollup
$3
javascript
import { JsonStreamStringify } from 'json-stream-stringify';
`$3
install @babel/runtime-corejs3 and corejs@3
javascript
import { JsonStreamStringify } from 'json-stream-stringify/polyfill';
import { JsonStreamStringify } from 'json-stream-stringify/module.polyfill'; // force ESM
`$3
javascript
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
`$3
javascript
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
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
$3
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.$3
Get current path begin serialized.
#### Returns
-
Array[String, Number]
Array of path Strings (keys of objects) and Numbers (index into arrays).
Can be transformed into an mpath with .join('.').
Useful in conjunction with .on('error', ...), for figuring out what path may have caused the error.Complete Example
`javascript
const { JsonStreamStringify } = require('json-stream-stringify');const jsonStream = new JsonStreamStringify({
// Promises and Streams may resolve more promises and/or streams which will be consumed and processed into json output
aPromise: Promise.resolve(Promise.resolve("text")),
aStream: ReadableObjectStream({a:1}, 'str'),
arr: [1, 2, Promise.resolve(3), Promise.resolve([4, 5]), ReadableStream('a', 'b', 'c')],
date: new Date(2016, 0, 2)
});
jsonStream.once('error', () => console.log('Error at path', jsonStream.stack.join('.')));
jsonStream.pipe(process.stdout);
`Output (each line represents a write from jsonStreamStringify)
text
{
"aPromise":
"text"
"aStream":
[
{
"a":
1
}
,
"str"
]
"arr":
[
1
,
2
,
3
,
[
4
,
5
]
,
"
a
b
c
"
],
"date":
"2016-01-01T23:00:00.000Z"
}
`Practical Example with Express + Mongoose
javascript
app.get('/api/users', (req, res, next) => {
res.type('json'); // Required for proper handling by test frameworks and some clients
new JsonStreamStringify(Users.find().stream()).pipe(res);
});
`$3
install
@types/readable-stream or @types/node or create your own stream.d.ts that exports a Readable` class.Copyright (c) 2016 Faleij faleij@gmail.com
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