Why the copy function doesn't work??

Question

https://code.sololearn.com/WtmD5WTSA621/?ref=app

Answer 1

select() only works on text input

Answer 2

JavaScript Console
TypeError: x.select is not a function

Answer 3

https://code.sololearn.com/WGDQS6PK88K0/?ref=app

see this code I used x.select() here too

Answer 4

So what Should I write insted of select??