How to HMAC-S256 encrypt a string in Node JS

I am pretty new to Node.

I am trying to get the following PHP code

$signature = base64_encode(hash_hmac('sha256', $canonicalString, $secret, true));
$signature = rtrim($signature,"=");

to work in node . Currently I have the following code implementation in node.

  return crypto.createHmac('sha256', key)

Still the service not getting authenticated.

Any help is much appreciated. Been stuck at the same line of code for more than a day.

Thank you