function isPromise()

in packages/mysql/lib/mysql_p.js [36:47]

• 7 lines of code
• 4 McCabe index (conditional complexity)

function isPromise(maybePromise) {
  if (maybePromise != null && maybePromise.then instanceof Function) {
    // mysql2 has a `Query` class with a `then` method which always throws an error when called.
    // We want to avoid calling this, so we need to check for more than just the presence of a `then` method.
    // See https://github.com/sidorares/node-mysql2/blob/dbb344e89a1cc8bb457b24e67b07cdb3013fe844/lib/commands/query.js#L38-L44
    // Since it's highly unlikely that any Promise implementation would name their class `Query`,
    // we can safely use this to determine whether or not this is actually a Promise.
    const constructorName = maybePromise.constructor != null ? maybePromise.constructor.name : undefined;
    return constructorName !== 'Query';
  }
  return false;
}