Why JavaScript over JQuery with webpages?

The only real reason is the cost of including jquery, which can be very minimal. Make no mistake, jquery is a library written in javascript, its still javascript, it still doesn't work if the user disables javascript in their browser, jquery just gives us a simplier syntax to do many common tasks we as developers want to do. It's really just an api for javascript when you think about it.

But jquery has weight, it's another http request, it's another file the browser must download, and than parse.

However, jquery is so popular, that I'm a big fan of using google's cdn to host jquery on my site as my primary, because if a users has already visited another site that used google's cdn to host the same version of jquery like me (and there is a decent chance of that), than when they hit my site, the browser will used it's cached version of jquery, giving my site a nice little performance bump. May only save milliseconds, but that starts to add up when we're looking for load times of less than one second.