@stdlib/utils-parse-ndjson

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parseNDJSON

Parse a string containing serialized newline-delimited JSON (NDJSON).

Installation

npm install @stdlib/utils-parse-ndjson

Usage

var parseNDJSON = require( '@stdlib/utils-parse-ndjson' );

parseNDJSON( str[, reviver] )

Parses a string as newline-delimited JSON.

var out = parseNDJSON( '{"beep":"boop"}\n{"example":42}' );
// returns [ { 'beep': 'boop' }, { 'example': 42 } ]

To transform the string being parsed, provide a reviver.

function reviver( key, value ) {
    if ( key === '' || key === 'beep' ) {
        return ( typeof value === 'string' ) ? value.toUpperCase() : value;
    }
    return ( typeof value === 'number' ) ? value * 2 : value;
}

var str = '{"beep":"boop"}\n{"value": 20}\n{"numbers": [1,2,3]}';
var out = parseNDJSON( str, reviver );
// returns [ { 'beep' : 'BOOP' }, { 'value': 40 }, { 'numbers': [ 2, 4, 6 ] } ]

Notes

• In contrast to the native JSON.parse(), this implementation parses string as newline-delimited JSON and returns an array of parsed JSONs.

  var out = JSON.parse( '{"beep":"boop"}\n{"foo":"baz"}' );
  // throws <SyntaxError>
  
  out = parseNDJSON( '{"beep":"boop"}\n{"foo":"baz"}' );
  // returns [ { 'beep': 'boop' }, { 'foo': 'baz' } ]

• In contrast to the native JSON.parse(), this implementation throws a TypeError if provided any value which is not a string.

  var out = JSON.parse( null );
  // returns null
  
  out = parseNDJSON( null );
  // throws <TypeError>

• In contrast to the native JSON.parse(), this implementation does not throw a SyntaxError if unable to parse a string as newline-delimited JSON.

  var out = parseNDJSON( '{"beep":boop}' );
  // returns <SyntaxError>
  
  out = JSON.parse( '{"beep":boop}' );
  // throws <SyntaxError>

• In contrast to the native JSON.parse(), this implementation throws a TypeError if provided a reviver argument which is not a function.

  var out = JSON.parse( '{"a":"b"}', [] );
  // returns { 'a': 'b' }
  
  out = parseNDJSON( '{"a":"b"}', [] );
  // throws <TypeError>

Examples

var parseNDJSON = require( '@stdlib/utils-parse-ndjson' );

var out = parseNDJSON( '{"name":"John"}\n{"name":"Doe"}' );
// returns [ { 'name': 'John' }, { 'name': 'Doe' } ]

function reviver( key, value ) {
    if ( key === 'name' ) {
        return value.toUpperCase();
    }
    return value;
}

out = parseNDJSON( '{"name":"John"}\n{"name":"Doe"}', reviver );
// returns [ { 'name': 'JOHN' }, { 'name': 'DOE' } ]

out = parseNDJSON( '{"name":John}\n{"name":Doe}' );
// returns <SyntaxError>

out = parseNDJSON( ' ' );
// returns []

out = parseNDJSON( '{}' );
// returns [ {} ]

out = parseNDJSON( '{"name":"Eve"}\n42\ntrue\n[1,2,3]' );
// returns [ { 'name': 'Eve' }, 42, true, [ 1, 2, 3 ] ]

out = parseNDJSON( '{"name":"John"}\r\n{"name":"Doe"}' );
// returns [ { 'name': 'John' }, { 'name': 'Doe' } ]

out = parseNDJSON( '{"name":"John"}\n{"name":"Doe"}\n' );
// returns [ { 'name': 'John' }, { 'name': 'Doe' } ]

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright 2016-2026. The Stdlib Authors.