npm package: @stdlib/utils-parse-ndjson
Description: Parse a string as Newline-Delimited JSON (NDJSON).
Author: The Stdlib Authors
Latest version: 0.1.2

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# parseNDJSON

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Parse a string containing serialized newline-delimited [JSON][json] (NDJSON).

<section class="installation">

## Installation

```bash
npm install @stdlib/utils-parse-ndjson
```

</section>

<section class="usage">

## Usage

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

#### parseNDJSON( str\[, reviver] )

Parses a `string` as `newline-delimited JSON`.

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

To transform the `string` being parsed, provide a `reviver`.

```javascript
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 ] } ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

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

    ```javascript
    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()`][json-parse], this implementation throws a TypeError if provided any value which is not a `string`.

    ```javascript
    var out = JSON.parse( null );
    // returns null

    out = parseNDJSON( null );
    // throws <TypeError>
    ```


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

    ```javascript
    var out = parseNDJSON( '{"beep":boop}' );
    // returns <SyntaxError>

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


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

    ```javascript
    var out = JSON.parse( '{"a":"b"}', [] );
    // returns { 'a': 'b' }

    out = parseNDJSON( '{"a":"b"}', [] );
    // throws <TypeError>
    ```

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
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' } ]
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/utils-parse-ndjson/main.svg
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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/utils-parse-ndjson/tree/deno
[deno-readme]: https://github.com/stdlib-js/utils-parse-ndjson/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/utils-parse-ndjson/tree/umd
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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-parse-ndjson/main/LICENSE

[json]: http://www.json.org/

[json-parse]: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse

</section>

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