I'm a self-taught aspiring front-end web developer and want to apply for junior web developer jobs. How much JavaScript and jQuery should I know and what should I know for an interview? I've done mostly HTML5 and CSS3 work and haven't really had the need to use much JavaScript. If a need arised that required some JavaScript I would just look up code and figure out how to implement it on my project. I have also been taking JavaScript and jQuery courses online but I don't quite feel confident enough yet to say I know it with a straight face.

So far I've had a few interviews but whenever the JavaScript question comes up I'm always up front and say that I understand JavaScript code and can modify the code to get it to work for a project but I'm not a JavaScript programmer and can't code from scratch just yet. My gut tells me this isn't what they want to hear. So does anyone have any advice on what I can do to boost my confidence with JavaScript / jQuery for interviews and make me more marketable? Or maybe I'm just looking at it the wrong way?