PHP's version_compare in JavaScript

How to use

You you can install via yarn add locutus and require this function via const version_compare = require('locutus/php/info/version_compare').

It is important to use a bundler that supports tree-shaking so that you only ship the functions that you actually use to your browser, instead of all of Locutus, which is massive. Examples are: Parcel, webpack, or rollup.js. For server-side use this is typically less of a concern.

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.

#	code	expected result
1	version_compare('8.2.5rc', '8.2.5a')	1
2	version_compare('8.2.50', '8.2.52', '<')	true
3	version_compare('5.3.0-dev', '5.3.0')	-1
4	version_compare('4.1.0.52','4.01.0.51')	1

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

module.exports = function version_compare(v1, v2, operator) {
  //       discuss at: https://locutus.io/php/version_compare/
  //      original by: Philippe Jausions (https://pear.php.net/user/jausions)
  //      original by: Aidan Lister (https://aidanlister.com/)
  // reimplemented by: Kankrelune (https://www.webfaktory.info/)
  //      improved by: Brett Zamir (https://brett-zamir.me)
  //      improved by: Scott Baker
  //      improved by: Theriault (https://github.com/Theriault)
  //        example 1: version_compare('8.2.5rc', '8.2.5a')
  //        returns 1: 1
  //        example 2: version_compare('8.2.50', '8.2.52', '<')
  //        returns 2: true
  //        example 3: version_compare('5.3.0-dev', '5.3.0')
  //        returns 3: -1
  //        example 4: version_compare('4.1.0.52','4.01.0.51')
  //        returns 4: 1

  // Important: compare must be initialized at 0.
  let i
  let x
  let compare = 0

  // vm maps textual PHP versions to negatives so they're less than 0.
  // PHP currently defines these as CASE-SENSITIVE. It is important to
  // leave these as negatives so that they can come before numerical versions
  // and as if no letters were there to begin with.
  // (1alpha is < 1 and < 1.1 but > 1dev1)
  // If a non-numerical value can't be mapped to this table, it receives
  // -7 as its value.
  const vm = {
    dev: -6,
    alpha: -5,
    a: -5,
    beta: -4,
    b: -4,
    RC: -3,
    rc: -3,
    '#': -2,
    p: 1,
    pl: 1,
  }

  // This function will be called to prepare each version argument.
  // It replaces every _, -, and + with a dot.
  // It surrounds any nonsequence of numbers/dots with dots.
  // It replaces sequences of dots with a single dot.
  //    version_compare('4..0', '4.0') === 0
  // Important: A string of 0 length needs to be converted into a value
  // even less than an unexisting value in vm (-7), hence [-8].
  // It's also important to not strip spaces because of this.
  //   version_compare('', ' ') === 1
  const _prepVersion = function (v) {
    v = ('' + v).replace(/[_\-+]/g, '.')
    v = v.replace(/([^.\d]+)/g, '.$1.').replace(/\.{2,}/g, '.')
    return !v.length ? [-8] : v.split('.')
  }
  // This converts a version component to a number.
  // Empty component becomes 0.
  // Non-numerical component becomes a negative number.
  // Numerical component becomes itself as an integer.
  const _numVersion = function (v) {
    return !v ? 0 : isNaN(v) ? vm[v] || -7 : parseInt(v, 10)
  }

  v1 = _prepVersion(v1)
  v2 = _prepVersion(v2)
  x = Math.max(v1.length, v2.length)
  for (i = 0; i < x; i++) {
    if (v1[i] === v2[i]) {
      continue
    }
    v1[i] = _numVersion(v1[i])
    v2[i] = _numVersion(v2[i])
    if (v1[i] < v2[i]) {
      compare = -1
      break
    } else if (v1[i] > v2[i]) {
      compare = 1
      break
    }
  }
  if (!operator) {
    return compare
  }

  // Important: operator is CASE-SENSITIVE.
  // "No operator" seems to be treated as "<."
  // Any other values seem to make the function return null.
  switch (operator) {
    case '>':
    case 'gt':
      return compare > 0
    case '>=':
    case 'ge':
      return compare >= 0
    case '<=':
    case 'le':
      return compare <= 0
    case '===':
    case '=':
    case 'eq':
      return compare === 0
    case '<>':
    case '!==':
    case 'ne':
      return compare !== 0
    case '':
    case '<':
    case 'lt':
      return compare < 0
    default:
      return null
  }
}

A community effort

Not unlike Wikipedia, Locutus is an ongoing community effort. Our philosophy follows The McDonald’s Theory. This means that we assimilate first iterations with imperfections, hoping for others to take issue with-and improve them. This unorthodox approach has worked very well to foster fun and fruitful collaboration, but please be reminded to use our creations at your own risk. THE SOFTWARE IS PROVIDED "AS IS" has never been more true than for Locutus.

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