M-x delete-trailing-whitespace
refacor
move codes
move codes
move codes
add comment
refactor
このコードはjsdoitから持ってきたやつで、効いてないので削除
remove debuggin code
move codes
indent
refactor
move codes
add how to use
indent
return 0 instead of  ""
rename function
move codes
set canvas background color by css, not by js