comparing version strings

gistfile1.js

// hacky numeric conversion:
//BUG: this will fail comparing "x.y" to "x.ypre"
var getVersion = function (versionString) {
  var values = versionString.split("."),
      version = 0,
      factor = 0.0001;
  
  for (var i = 0, l = values.length; i < l; i++) {
    version += parseInt(values[i], 10) * Math.pow(factor, i);
  }

  return version;
};

// Example usage:
if (getVersion(jQuery.fn.jquery) >= getVersion("1.3")) {
  // don't use @ in attr selectors
}



// quick & dirty version:
//BUG: this will fail comparing "x.y" to "x.y.0" 
//BUG: this will fail comparing "x.y" to "x.ypre"
var versionGTE = function (valueA, valueB) {
  var values = [valueA, valueB];
  values.sort();
  // if valueA > valueB, values will have switched
  return (values[1] === valueA);
};

// compact version:
var versionGTE = function (valueA, valueB) {
  return ([valueA, valueB].sort()[1] === valueA);
};

// Example usage:
if (versionGTE(jQuery.fn.jquery, "1.3")) {
  // don't use @ in attr selectors
}



// long & hairy version:
var versionCompare = function (versionStringA, versionStringB) {
  // quick test of equality before digging in
  if (versionStringA === versionStringB) return 0;

  var versionedAlpha = /[a-z]+(\d+)/gi,
      getArray = function (verString) {
        // replace rc1, rc2, beta3, etc with .-1.1, .-1.2, .-1.3, etc
        return verString.replace(versionedAlpha, ".-1.$1").split(".");
      },
      valuesA = getArray(versionStringA),
      valuesB = getArray(versionStringB),
      maxLength = Math.max(valuesA.length, valuesB.length),
      hasLetters = /[a-z]/gi,
      // assume any version with letters is -1 (pre, rc, etc)
      // also assume that any null entries are 0 (1.5 === 1.5.0)
      parseVersion = function (verString) {
        return (verString) ? (hasLetters.test(verString)) ? -1 : parseInt(verString, 10) : 0;
      };

  // verify both arrays are the same size
  valuesA.length = maxLength;
  valuesB.length = maxLength;

  for (var i = 0; i < maxLength; i++) {
    var valueA = parseVersion(valuesA[i]),
        valueB = parseVersion(valuesB[i]);

    if (valueA < valueB) {
      return -1;
    } else if (valueA > valueB) {
      return 1;
    }
  }

  // all equal at this point
  return 0;
};

// Example usage:
if (versionCompare(jQuery.fn.jquery, "1.3") >= 0) {
  // don't use @ in attr selectors
}

https://gist.github.com/2664255

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