This class generates an upper and lower bound of a hex string (ie md5 or sha1 hash)

SelectNextLimit.js

var SelectNextLimit = function(upper,res) {
  
  var base = parseInt(upper,16);
  var resolution = parseInt(res, 16);
  
  var upper,lower;
  
  this.next = function() {
      upper = (base).toString(16);

      base = base - resolution;

      lower = (base).toString(16);

      return {upper:upper,lower:lower};
  };
};