For comparing semantic versions

compareVersions.js

function compareVersions(v1, v2) { // Returns the larger of the two. or "equal"
  v1Array = v1.split(".");
  v2Array = v2.split(".");
  for(var i=0; i<v1Array.length;i++){v1Array[i] = parseInt(v1Array[i])};
  for(var i=0; i<v2Array.length;i++){v2Array[i] = parseInt(v2Array[i])};

  if (v1Array.length != 3 || v2Array.length != 3){
    return "Both versions need to be x.y.z";
  } else {
    if (v1Array[0]>v2Array[0]){
      return v1;
    } else if (v1Array[0]<v2Array[0]) {
      return v2;
    } else {
      if (v1Array[1]>v2Array[1]){
        return v1;
      } else if (v1Array[1]<v2Array[1]) {
        return v2;
      } else {
        if (v1Array[2]>v2Array[2]){
          return v1;
        } else if (v1Array[2]<v2Array[2]) {
          return v2;
        } else {
          return "equal";
        }
      }
    }
  }
}