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Read JSON

Read a file as JSON.

Installation

npm install @stdlib/fs-read-json

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var readJSON = require( '@stdlib/fs-read-json' );

readJSON( file[, options], clbk )

Asynchronously reads a file as JSON.

var join = require( 'path' ).join;

readJSON( join( __dirname, 'package.json' ), onJSON );

function onJSON( error, data ) {
    if ( error ) {
        throw error;
    }
    console.dir( data );
}

The function accepts the following options:

• encoding: file encoding.
• flag: file status flag.
• reviver: JSON transformation function.

The options parameter may also be a string specifying the file encoding.

var join = require( 'path' ).join;

readJSON( join( __dirname, 'package.json' ), 'utf8', onJSON );

function onJSON( error, data ) {
    if ( error ) {
        throw error;
    }
    console.dir( data );
}

readJSON.sync( file[, options] )

Synchronously reads a file as JSON.

var join = require( 'path' ).join;
var instanceOf = require( '@stdlib/assert-instance-of' );

var out = readJSON.sync( join( __dirname, 'package.json' ) );
if ( instanceOf( out, Error ) ) {
    throw out;
}
console.dir( out );

The function accepts the same options as readJSON() above.

Notes

• If the encoding option is set to utf8 and the file has a UTF-8 byte order mark (BOM), the byte order mark is removed before attempting to parse as JSON.

Examples

var join = require( 'path' ).join;
var readJSON = require( '@stdlib/fs-read-json' );

var file = join( __dirname, 'package.json' );

// Synchronously read file contents...
var data = readJSON.sync( file, 'utf8' );
// returns <Object>

data = readJSON.sync( 'beepboop', {
    'encoding': 'utf8'
});
// returns <Error>

// Asynchronously read file contents...
readJSON( file, onJSON );
readJSON( 'beepboop', onJSON );

function onJSON( error, data ) {
    if ( error ) {
        if ( error.code === 'ENOENT' ) {
            console.error( 'JSON file does not exist.' );
        } else {
            throw error;
        }
    } else {
        console.log( 'Package description: %s', data.description );
    }
}

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See Also

• @stdlib/fs-read-file: read the entire contents of a file.

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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 © 2016-2024. The Stdlib Authors.