"Is there any hidden highlight feature in InDesign plugin?"
Yes (apparently, as you said you found one). A plugin can add such functionality to InDesign.
".. then can we do the same thing in InDesign javascript?" No. Javascript cannot add such functionality. Javascript only allows the interface with InDesign, it does not add or remove anything from InDesign itself.
I am guessing you have a series of follow-up questions, but those are going to be the same as a fairly recent, long series of Absolute Beginners' problem threads. Let's get some possible (mis)conceptions out of the way first, then.
1. No, not Javascript nor any other end-user programming language can add such advanced functions. These need a plugin.
2. Yes I am positively sure. It cannot be done, by design.
3. No, plugins cannot be written in Javascript. For that you need the Adobe InDesign SDK.
4. No, that SDK requires plugins to be written in C++, not in Java/Javascript/AppleScript/Windows batch files/xxx (for every programming language 'xxx' which does not equal 'C++')
5. No, you cannot copy a random SDK example and easily modify this to add all those fancy new functions that you want. It is a bit harder than that.
6. No, the SDK requires an advanced level of C++ before you start programming with it. Not during, not after. If you have 0% knowlegde of C++ then you are not prepared to use the SDK. There is no Beginner's Guide -- because it assumes there are no "beginners"; you must already be proficient in C++. (As well as all strictly InDesign related stuff, such as its DOM, the various interfaces, and more like that. I.e., even if you know how to program but you don't know anything about InDesign, then the SDK documentation will still not help you understand it.)
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