js determines that the IE browser version is too low sample code_javascript skills

I made a very simple example to determine whether the IE browser version is too low
The structure of the example is as follows. In fact, it is enough to introduce jquery into a page. By the way, I made a standard structure (note that it is used when the IE6 and IE7 versions are lower. Only then did I see its prompt effect)

Copy the code The code is as follows: