Checks if input is a valid UUID (any version, includes nil and GUID) as per RFC 4122 - https://tools.ietf.org/html/rfc4122

isUUID.js

// Fiddle - https://jsfiddle.net/ratpik/azf5a9bv/3/
var UUIDIndex = {0:8, 1:4, 2:4, 3:4, 4:12};

function isHex(h, index) {
  if (UUIDIndex[index] !== _.size(h)) return false;
  
  var a = parseInt(h, 16); 
  return !isNaN(a) && 
    a.toString(16) === _.toLower(h) ||
    _.join(_.times(_.size(h), _.constant(0)), '') === _.toLower(h);
}

//All UUIDs are of the format 8-4-4-4-12
function isValidUUID(id) {
 return id && 
   (id = id.split('-')) && 
   id.length === 5 &&
   _.chain(id)
    .map(isHex)
    .reduce(function (isHex, result) { return (result = result && isHex); })
    .value();
}

//The different UUID versions only differ in the way they are generated
//true - Version 1 UUID (Timestamp and MAC)
console.log(isValidUUID('aba8a19c-2ff0-11e7-93ae-92361f002671'));
//true - Version 4 UUID (Pseudorandom)
console.log(isValidUUID('a4df3fd6-ac7a-499f-9575-a5a5411a6ce7'));
//true - nil UUID
console.log(isValidUUID('00000000-0000-0000-0000-000000000000'));
//true - Microsoft GUID 
console.log(isValidUUID('d5fdb8ce-4864-4f18-ad52-1f664a1689b5'));
//false
console.log(isValidUUID('123e4567'));
//false - Looks like GUID
console.log(isValidUUID('d5fdb8ce-4864-4h18-ad52-1f664a1689b5'));