Please fix it?

Question

I want to make a selecting option with javascript.
https://code.sololearn.com/WVZrac0Y2GdG/?ref=app

Answer 1

https://code.sololearn.com/WOJDe329vdx6/?ref=app

Answer 2

Really its amazing. Thank you.
But what is my foult??

Answer 3

It is SL specific that you need to call your code at window. onload

Answer 4

after here was a little logical bug
select.insertBefore(select, option.lastChild);

Answer 5

Ohh thanks Oma Falk