PHP's is_numeric in JavaScript

Here’s what our current JavaScript equivalent to PHP's is_numeric looks like.

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module.exports = function is_numeric (mixedVar) { // eslint-disable-line camelcase
// discuss at: http://locutus.io/php/is_numeric/
// original by: Kevin van Zonneveld (http://kvz.io)
// improved by: David
// improved by: taith
// bugfixed by: Tim de Koning
// bugfixed by: WebDevHobo (http://webdevhobo.blogspot.com/)
// bugfixed by: Brett Zamir (http://brett-zamir.me)
// bugfixed by: Denis Chenu (http://shnoulle.net)
// example 1: is_numeric(186.31)
// returns 1: true
// example 2: is_numeric('Kevin van Zonneveld')
// returns 2: false
// example 3: is_numeric(' +186.31e2')
// returns 3: true
// example 4: is_numeric('')
// returns 4: false
// example 5: is_numeric([])
// returns 5: false
// example 6: is_numeric('1 ')
// returns 6: false

var whitespace = [
' ',
'\n',
'\r',
'\t',
'\f',
'\x0b',
'\xa0',
'\u2000',
'\u2001',
'\u2002',
'\u2003',
'\u2004',
'\u2005',
'\u2006',
'\u2007',
'\u2008',
'\u2009',
'\u200a',
'\u200b',
'\u2028',
'\u2029',
'\u3000'
].join('')

// @todo: Break this up using many single conditions with early returns
return (typeof mixedVar === 'number' ||
(typeof mixedVar === 'string' &&
whitespace.indexOf(mixedVar.slice(-1)) === -1)) &&
mixedVar !== '' &&
!isNaN(mixedVar)
}
[ View on GitHub | Edit on GitHub | Source on GitHub ]

How to use

You you can install via npm install locutus and require it via require('locutus/php/var/is_numeric'). You could also require the var module in full so that you could access var.is_numeric instead.

If you intend to target the browser, you can then use a module bundler such as Browserify, webpack or rollup.js.

ES5/ES6

This function targets ES5, but as of Locutus 2.0.2 we also support ES6 functions. Locutus transpiles to ES5 before publishing to npm.

A community effort

Not unlike Wikipedia, Locutus is an ongoing community effort. Our philosophy follows The McDonald’s Theory. This means that we don't consider it to be a bad thing that many of our functions are first iterations, which may still have their fair share of issues. We hope that these flaws will inspire others to come up with better ideas.

This way of working also means that we don't offer any production guarantees, and recommend to use Locutus inspiration and learning purposes only.

Examples

Please note that these examples are distilled from test cases that automatically verify our functions still work correctly. This could explain some quirky ones.

#codeexpected result
1is_numeric(186.31)true
2is_numeric('Kevin van Zonneveld')false
3is_numeric(' +186.31e2')true
4is_numeric('')false
5is_numeric([])false
6is_numeric('1 ')false

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