This whole thing is a waste of time! The printed output for the tax return doesn't contain any of the information you enter. All those dates, kens and machis are just thrown away. The only thing that matters is the total. Fuuuuuuuuuuuuuuuu...!
This is a hack for the furusato nozei entry page of the Japanese tax entry form (the version that produces a PDF to print out, I have no idea about the e-tax thing).
That form is very frustrating. It's all drop-downs. I have all of my data already in digital form. Drop-downs mean I can't copy and paste. If you did furusato to a town in Hokkaido good luck finding the town from the list of ~100.
Also the date entry is particularly special. The year is fixed, it can only be 2019 but in the Japanese calendar, 2019 from Jan-Apr is 平成31 and from May-Dec is 令和1. So before you can select a month, you must select an era. Once the era is chosen, the year is fixed (but there's still a drop-down for it for added confusion) then you can select a month (1-4 or 5-12, depending on the era). I can't think of a worse way of having a human input a date.
WARNING Never paste random JS from untrusted sites into your JS console. I repeat, DO NOT FOLLOW THESE INSTRUCTIONS IF YOU DO NOT UNDERSTAND THE DANGERS.
If you do decide to do this, don't blame me if you lose all your work. This code worked for me it may not work for you. It might do something much worse for you!
When you get the furusato form open in your browser (I'm assuming chrome), hit CTRL-i to open the debug tools. Copy the JS from here and paste it into the JS console.
You're done.
You'll see some input fields have appeared at the top of the form. You have 2 choices.
The CSV field lets you paste in 1 comma-separated entry.
It expects YYYY-MM-DD,Prefecture,Town (optional),Amount.
E.g. 2019-12-27,佐賀県,上峰町,35000.
When you move out of the field,
it populates the fields below
and (hopefully) sets all of the drop-downs correctly.
All you have to do is click the button at the bottom of the page.
If you don't have your data in CSV you can just type things into the individual fields and click "go".
If you press c on your keyboard
focus moves to the CSV field.
If you needed to actually press the letter c,
I'm sorry.
You can paste windows.onkeypress = undefined into the JS console.
At the moment if there are any errors, e.g. a date that can't be parsed or it can't find the town you entered, you get a message in red below the input boxes and it throws an exception which you can see on the JS console.
Feel free to do whatever you want this. Hopefully it works with next year's form with minor modifications.
I might turn this in a chrome extension however I think the idea of an extension that has access to the tax site is pretty shady, so I don't know.