How well do I need to know Javascript to become a front end developer?

I am an aspiring front end web developer - I have been on code academy for a couple of months, and I have watched good youtube tutorial videos which show how websites are structured and designed to look good and been experimenting with what I have been learning

I have learned HTML and CSS up to a proficient standard and am currently learning twitter bootstrap and jquery as well as HTML5, I took the code academy course in javascript but find it a difficult language

My friend advised me that for anything I learn in jQuery i should know how to do it in javascript, when I look at the javascript code needed to do the stuff jQuery does it looks rather daunting. I understood how to validate forms with javascript and do the maths for loan calculations, but all the animation stuff looked baffling

My question is how much expertise will I need in javascript if I want to get hired as a front end developer, assuming that I am good with HTML5,CSS,bootstrap and Jquery, and also what other things will I need to learn to maximize my employment chances? I really don't like the back end developer stuff and find it boring - such as the object orientated programing