My question simply is: I can't show any definition when hover on my specially my javaScript code even by hovering or pressing ctrl+k or ctrl+space I tried my ways but I can't reach this point
Installing the Visual Studio IntelliCode extension will fix that.
But even with that installed, since JavaScript is a loosely typed language, things like variables will just show any when you hover over them.
Installing IntelliSense removed this issue for me.