isHexa = function isHexa(value) {
  if (!_.isString(value)) {
    return false;
  }
  return /^[0-9a-fA-F]+$/.test(value);
}
Determines whether a string contains only hexadecimal values

@name JSUtil.isHexa
@param {string} value
@return {boolean} true if the string is the hexa representation of a number