README.md

About stdlib...

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isJSON

Test if a value is a parseable JSON string.

Installation

npm install @stdlib/assert-is-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 isJSON = require( '@stdlib/assert-is-json' );

isJSON( value )

Tests if a value is a parseable JSON string.

var value = '{"a":5}';

var bool = isJSON( value );
// returns true

Notes

• The implementation validates that the input value is a string literal. For all other inputs, the method returns false.

• The implementation validates that a string begins with either [ or { and ends with a corresponding ] or }, respectively. Hence, the method will return false for the following strings, despite JSON.parse accepting their input:

  • '<number>' (e.g., '5')
  • '<boolean>' (e.g., 'true')
  • 'null'

• The implementation wraps JSON.parse inside a try/catch. Hence, this function cannot be optimized by the compiler during runtime. Nevertheless, using this function is better than embedding a try/catch within a larger function which could be optimized in the absence of a try/catch.

Examples

var isJSON = require( '@stdlib/assert-is-json' );

var bool = isJSON( '{"a":5}' );
// returns true

bool = isJSON( '{a":5}' );
// returns false

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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.