PHP's is_nan in TypeScript

How to use

Install via yarn add locutus and import: import { is_nan } from 'locutus/php/math/is_nan'.

Or with CommonJS: const { is_nan } = require('locutus/php/math/is_nan')

Use a bundler that supports tree-shaking so you only ship the functions you actually use. Vite, webpack, Rollup, and Parcel all handle this. For server-side use this is less of a concern.

Examples

These examples are extracted from test cases that automatically verify our functions against their native counterparts.

#	code	expected result
1	is_nan(NaN)	true
2	is_nan(0)	false

Here's what our current TypeScript equivalent to PHP's is_nan looks like.

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

Copy code

import type { PhpRuntimeValue } from '../_helpers/_phpTypes.ts'

type NumberCheckValue = PhpRuntimeValue

export function is_nan(val: NumberCheckValue): boolean {
  //  discuss at: https://locutus.io/php/is_nan/
  // original by: Onno Marsman (https://twitter.com/onnomarsman)
  //    input by: Robin
  //   example 1: is_nan(NaN)
  //   returns 1: true
  //   example 2: is_nan(0)
  //   returns 2: false

  let warningType = ''

  if (typeof val === 'number' && isNaN(val)) {
    return true
  }

  // Some errors for maximum PHP compatibility
  if (typeof val === 'object') {
    warningType = Array.isArray(val) ? 'array' : 'object'
  } else if (typeof val === 'string' && !/^[+-]?\d/.test(val)) {
    // simulate PHP's behaviour: '-9a' doesn't give a warning, but 'a9' does.
    warningType = 'string'
  }
  if (warningType) {
    throw new Error('Warning: is_nan() expects parameter 1 to be double, ' + warningType + ' given')
  }

  return false
}

export function is_nan(val) {
  //  discuss at: https://locutus.io/php/is_nan/
  // original by: Onno Marsman (https://twitter.com/onnomarsman)
  //    input by: Robin
  //   example 1: is_nan(NaN)
  //   returns 1: true
  //   example 2: is_nan(0)
  //   returns 2: false

  let warningType = ''

  if (typeof val === 'number' && isNaN(val)) {
    return true
  }

  // Some errors for maximum PHP compatibility
  if (typeof val === 'object') {
    warningType = Array.isArray(val) ? 'array' : 'object'
  } else if (typeof val === 'string' && !/^[+-]?\d/.test(val)) {
    // simulate PHP's behaviour: '-9a' doesn't give a warning, but 'a9' does.
    warningType = 'string'
  }
  if (warningType) {
    throw new Error('Warning: is_nan() expects parameter 1 to be double, ' + warningType + ' given')
  }

  return false
}

Improve this function

Locutus is a community effort following The McDonald's Theory: we ship first iterations, hoping others will improve them. If you see something that could be better, we'd love your contribution.

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