For this request
influxDb.grantPrivilege('571dbd9672379792340f87d2', 'WRITE', 'test');
I get this error

Unhandled rejection Error: A 400 Bad Request error occurred: {"error":"error parsing query: found TO, expected ON at line 1, char 13"}

But in the same time this works:
influxDb.query('GRANT WRITE ON test TO "571dbd9672379792340f87d2"', {database: 'test'});

node-influx v5.0.0
influx v1.0.2