function(e){} これが分かり易い https://www.youtube.com/watch?v=OiWLIe_Cz6E

fields_forはnewとeditでは若干記述が異なるので注意 https://qiita.com/kouuuki/items/5daf2b5f34273d8457f7 その他参考記事 https://qiita.com/gakinchoy7/items/ac1d8e64e33c3ddd377b https://qiita.com/shota0701nemoto/items/2d4889a59b50a608255f