The months and days of week are 0-indexed. The dates of month are 1-indexed. Same as javascriopt. You always have to be careful with this API, but it helps to r

The months and days of week are 0-indexed. The dates of month are 1-indexed. Same as javascriopt. You always have to be careful with this API, but it helps to remember that they return an index in an array for the items that have a name in English (“January” and “Sunday”).