[invisal]

How is hiding the HTML and Javascript code protect you from thieves?
What do you mean by thieves? stole your code? or hack into your website?

If it is server-side script like PHP, you don't need to hide it
from view source, because it does not show in view source.

If it is client-side script like Javascript, you may try
"javascript obfuscator", basically, it makes your code very hard
to read, but the code is still there.