function version_compare (v1, v2, operator) {
  // http://kevin.vanzonneveld.net
  // +      original by: Philippe Jausions (http://pear.php.net/user/jausions)
  // +      original by: Aidan Lister (http://aidanlister.com/)
  // + reimplemented by: Kankrelune (http://www.webfaktory.info/)
  // +      improved by: Brett Zamir (http://brett-zamir.me)
  // +      improved by: Scott Baker
  // +      improved by: 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
  // BEGIN REDUNDANT
  this.php_js = this.php_js || {};
  this.php_js.ENV = this.php_js.ENV || {};
  // END REDUNDANT
  // Important: compare must be initialized at 0.
  var i = 0,
    x = 0,
    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.
    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
    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.
    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;
  }
}

version_compare('8.2.5rc', '8.2.5a');

1

version_compare('8.2.50', '8.2.52', '<');

true

version_compare('5.3.0-dev', '5.3.0');

-1