There is no protection on the internet. To display something on the respondents screen it is already saved on their computer (temporarily) and can be accessed in the cache. So even if you put a script that for example disallows to right click on the page (to avoid copying text, etc), there is always the option to switch Javascript off. Or you simply make a screenshot.
So you might make it slightly more difficult for someone who has no idea how things work, but someone with half decent internet knowledge will know how to get around your little barriers.
In my opinion, it is not even worth the effort.
I answer at the LimeSurvey forum in my spare time, I'm not a LimeSurvey GmbH employee.
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