Migration from 1.x to 2.x

Migrating from 1.x to 2.x

This guide covers breaking changes and how to update your code.

Overview of changes

• Source moved from root to src/.
• Class-based Transform streams replaced with factory functions returning flushable closures.
• Import paths changed (lowercase, .js extension).
• stream-chain 3.x handles backpressure via flushable, many, none, gen, asStream.
• TypeScript declarations included (.d.ts files).
• Test framework changed from heya-unit to tape-six.

Import path changes

1.x	2.x
require('stream-csv-as-json')	require('stream-csv-as-json') (unchanged)
require('stream-csv-as-json/Parser')	require('stream-csv-as-json/parser.js')
require('stream-csv-as-json/AsObjects')	require('stream-csv-as-json/as-objects.js')
require('stream-csv-as-json/Stringer')	require('stream-csv-as-json/stringer.js')

API changes

Parser

1.x — class with constructor and static factories:

const Parser = require('stream-csv-as-json/Parser');
const p = new Parser(options);
// or
const {parser} = require('stream-csv-as-json/Parser');
const p = parser(options); // returns a Parser instance

2.x — factory function:

const parser = require('stream-csv-as-json/parser.js');
const fn = parser(options); // flushable function for chain()
const stream = parser.asStream(options); // Duplex stream

new Parser() is no longer available. Use parser() in a chain() pipeline or parser.asStream() for a standalone Duplex stream.

AsObjects

1.x:

const {asObjects} = require('stream-csv-as-json/AsObjects');
const {withParser} = require('stream-csv-as-json/AsObjects');

2.x:

const asObjects = require('stream-csv-as-json/as-objects.js');
asObjects(options); // flushable function
asObjects.asStream(options); // Duplex stream
asObjects.withParser(options); // parser + asObjects pipeline
asObjects.withParserAsStream(options); // same, as Duplex

Note: withParser is now a method on asObjects, not a separate named export.

Stringer

1.x:

const {stringer} = require('stream-csv-as-json/Stringer');
const s = stringer(options); // returns a Stringer instance

2.x:

const stringer = require('stream-csv-as-json/stringer.js');
const fn = stringer(options); // flushable function for chain()
const stream = stringer.asStream(options); // Duplex stream

Main module

1.x:

const make = require('stream-csv-as-json');
const {Parser, parser} = require('stream-csv-as-json');

2.x:

const make = require('stream-csv-as-json');
const {parser} = require('stream-csv-as-json');

make(options) still returns a stream with emit() applied. The Parser class export is removed — use parser instead.

stream-chain

1.x used stream-chain 2.x with {chain} destructuring:

const {chain} = require('stream-chain');

2.x uses stream-chain 3.x with a default export:

const chain = require('stream-chain');

Removed APIs

Removed	Replacement
new Parser(options)	parser(options) or parser.asStream(options)
Parser.make(options)	parser(options)
Parser.parser(options)	parser(options)
new AsObjects(options)	asObjects(options) or asObjects.asStream(options)
AsObjects.make(options)	asObjects(options)
new Stringer(options)	stringer(options) or stringer.asStream(options)
Stringer.make(options)	stringer(options)
make.Constructor / make.Parser	parser (the factory)

Quick migration recipe

Before (1.x):

const {chain} = require('stream-chain');
const {parser} = require('stream-csv-as-json');
const {asObjects} = require('stream-csv-as-json/AsObjects');
const {streamValues} = require('stream-json/streamers/StreamValues');

chain([fs.createReadStream('data.csv'), parser(), asObjects(), streamValues(), ({value}) => console.log(value)]);

After (2.x):

const chain = require('stream-chain');
const {parser} = require('stream-csv-as-json');
const asObjects = require('stream-csv-as-json/as-objects.js');

chain([fs.createReadStream('data.csv'), parser(), asObjects()]);

Components are now plain functions — they work directly in chain() without needing streamValues() to assemble objects. The token stream is the same, so stream-json utilities still work if you need them.

Options unchanged

All parser, asObjects, and stringer options (packStrings, packValues, streamStrings, streamValues, separator, packKeys, streamKeys, useStringValues, useValues, fieldPrefix) work exactly as before with the same defaults and resolution logic.