Test if a value is a probability.
npm install @stdlib/assert-is-probabilityWe believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js. The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases. When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there. To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
About stdlib...
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Test if a value is a probability.
A probability is defined as a numeric value on the interval [0,1].
``bash`
npm install @stdlib/assert-is-probability
`javascript`
var isProbability = require( '@stdlib/assert-is-probability' );
#### isProbability( value )
Tests if a value is a probability.
`javascript
var Number = require( '@stdlib/number-ctor' );
var bool = isProbability( 0.5 );
// returns true
bool = isProbability( new Number( 0.5 ) );
// returns true
bool = isProbability( 3.14 );
// returns false
bool = isProbability( -5.0 );
// returns false
bool = isProbability( NaN );
// returns false
bool = isProbability( null );
// returns false
`
#### isProbability.isPrimitive( value )
Tests if a value is a primitive probability.
`javascript
var Number = require( '@stdlib/number-ctor' );
var bool = isProbability.isPrimitive( 0.33 );
// returns true
bool = isProbability.isPrimitive( new Number( 0.33 ) );
// returns false
`
#### isProbability.isObject( value )
Tests if a value is a Number object having a value which is a probability.
`javascript
var Number = require( '@stdlib/number-ctor' );
var bool = isProbability.isObject( 0.11 );
// returns false
bool = isProbability.isObject( new Number( 0.11 ) );
// returns true
`
`javascript
var Number = require( '@stdlib/number-ctor' );
var isProbability = require( '@stdlib/assert-is-probability' );
var bool = isProbability( 0.5 );
// returns true
bool = isProbability( new Number( 0.5 ) );
// returns true
bool = isProbability( 0.0 );
// returns true
bool = isProbability( 1.0 );
// returns true
bool = isProbability( 3.14 );
// returns false
bool = isProbability( -5.0 );
// returns false
bool = isProbability( NaN );
// returns false
bool = isProbability( '0.5' );
// returns false
bool = isProbability( null );
// returns false
`
*
- [@stdlib/assert-is-number][@stdlib/assert/is-number]: test if a value is a number.
*
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]
---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/assert-is-probability.svg
[npm-url]: https://npmjs.org/package/@stdlib/assert-is-probability
[test-image]: https://github.com/stdlib-js/assert-is-probability/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/assert-is-probability/actions/workflows/test.yml?query=branch:v0.2.3
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/assert-is-probability/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/assert-is-probability?branch=main
[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
[chat-url]: https://stdlib.zulipchat.com
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[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/assert-is-probability/tree/deno
[deno-readme]: https://github.com/stdlib-js/assert-is-probability/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/assert-is-probability/tree/umd
[umd-readme]: https://github.com/stdlib-js/assert-is-probability/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/assert-is-probability/tree/esm
[esm-readme]: https://github.com/stdlib-js/assert-is-probability/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/assert-is-probability/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/assert-is-probability/main/LICENSE
[@stdlib/assert/is-number]: https://www.npmjs.com/package/@stdlib/assert-is-number