PHP's fmod in TypeScript

How to use

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

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

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	fmod(5.7, 1.3)	0.5
2	fmod(10, 1)	0

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

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

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export function fmod(x: number | string, y: number | string): number {
  //      discuss at: https://locutus.io/php/fmod/
  // parity verified: PHP 8.3
  //     original by: Onno Marsman (https://twitter.com/onnomarsman)
  //        input by: Brett Zamir (https://brett-zamir.me)
  //     bugfixed by: Kevin van Zonneveld (https://kvz.io)
  //     bugfixed by: Irina (https://github.com/dekairi)
  //       example 1: fmod(5.7, 1.3)
  //       returns 1: 0.5
  //       example 2: fmod(10, 1)
  //       returns 2: 0

  let tmp: RegExpMatchArray | null
  let tmp2
  let p = 0
  let pY = 0
  let l = 0.0
  let l2 = 0.0
  const normalizedX = Number(x)
  const normalizedY = Number(y)

  tmp = normalizedX.toExponential().match(/^.\.?(.*)e(.+)$/)
  if (!tmp) {
    return NaN
  }
  p = Number.parseInt(tmp[2] ?? '0', 10) - (tmp[1] ?? '').length
  tmp = normalizedY.toExponential().match(/^.\.?(.*)e(.+)$/)
  if (!tmp) {
    return NaN
  }
  pY = Number.parseInt(tmp[2] ?? '0', 10) - (tmp[1] ?? '').length

  if (pY > p) {
    p = pY
  }

  tmp2 = normalizedX % normalizedY

  if (p < -100 || p > 20) {
    // toFixed will give an out of bound error so we fix it like this:
    l = Math.round(Math.log(tmp2) / Math.log(10))
    l2 = Math.pow(10, l)

    return Number((tmp2 / l2).toFixed(l - p)) * l2
  } else {
    return parseFloat(tmp2.toFixed(Math.abs(p)))
  }
}

export function fmod(x, y) {
  //      discuss at: https://locutus.io/php/fmod/
  // parity verified: PHP 8.3
  //     original by: Onno Marsman (https://twitter.com/onnomarsman)
  //        input by: Brett Zamir (https://brett-zamir.me)
  //     bugfixed by: Kevin van Zonneveld (https://kvz.io)
  //     bugfixed by: Irina (https://github.com/dekairi)
  //       example 1: fmod(5.7, 1.3)
  //       returns 1: 0.5
  //       example 2: fmod(10, 1)
  //       returns 2: 0

  let tmp
  let tmp2
  let p = 0
  let pY = 0
  let l = 0.0
  let l2 = 0.0
  const normalizedX = Number(x)
  const normalizedY = Number(y)

  tmp = normalizedX.toExponential().match(/^.\.?(.*)e(.+)$/)
  if (!tmp) {
    return NaN
  }
  p = Number.parseInt(tmp[2] ?? '0', 10) - (tmp[1] ?? '').length
  tmp = normalizedY.toExponential().match(/^.\.?(.*)e(.+)$/)
  if (!tmp) {
    return NaN
  }
  pY = Number.parseInt(tmp[2] ?? '0', 10) - (tmp[1] ?? '').length

  if (pY > p) {
    p = pY
  }

  tmp2 = normalizedX % normalizedY

  if (p < -100 || p > 20) {
    // toFixed will give an out of bound error so we fix it like this:
    l = Math.round(Math.log(tmp2) / Math.log(10))
    l2 = Math.pow(10, l)

    return Number((tmp2 / l2).toFixed(l - p)) * l2
  } else {
    return parseFloat(tmp2.toFixed(Math.abs(p)))
  }
}

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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