Getting all the fields of a custom record

Good morning,
I'm looking for a way to extract, with SuiteScript, the names of the custom fields added to a custom record type.

For example if there's a custom record type called "customrecord144", and it has two fields "custrecord241" and "custrecord242".

Is there a function that, given the name of the record type ("customrecord144"), returns an array of objects describing the 2 fields, "custrecord241" and "custrecord242".

I've tried with

 var oCustRecConfig = nlapiLoadConfiguration('customrecord144'); 

but it raises an exception "Invalid type customrecord144, use nlapiLoadRecord".

Any suggestion?

Thank you,
Alessio