Insert today's date PLUS 1 month

I know the code below is wrong. Could someone give me a hand calculating today’s date plus 1 month and 1 year? to be able to insert in a collection.

let toInsert = {
“startDate”: new Date(),
“monthDate”: new Date() + 1 month?
“yearDate”: new Date() + 1 year?
}
wixData.insert(“Members”, toInsert);

This is not a Wix Code problem, but a JavaScript question. Look here: JavaScript Date Reference