createJSONStream.md

createJSONStream(value, replacer = undefined, space = 0)

Create a Node.js stream that outputs a JSON string

Syntax

Express.js:

import { createJSONStream } from 'progressive-json/server';

/* ... */

app.get('/api/:table', (req, res) => {
  const { table } = req.params;
  const results = loadRecords(table);
  const stream = createJSONStream(results);
  stream.pipe(res);
});

Fastify:

import { createJSONStream } from 'progressive-json/server';

/* ... */

fastify.get('/api/:table', async (req) => {
  const { table } = req.params;
  const results = loadRecords(table);
  return createJSONStream(results);
});

Parameters

• value - <AsyncGenerator> or <Generator> or <Promise> or <any> The value to convert to a JSON string. It can be an ordinary JavaScript value or a special construct like async generator.
• replacer - <Function> or <string[]> A function that alters the behavior of the stringification process
• space - <number> A number that's used to insert white space into the output JSON string for readability purposes. Cannot be a string.
• return <Readable> A Node.js stream

Consult documentation of JSON.stringify for more details about replacer.

Notes

createJSONStream is capable of handling output from asynchronous toJSON methods.

Use countGenerated to send the number of items that a generator will eventually produce.

Use deferred to send a value that will be calculated later, at the moment when it is needed.