Thanks to my higher education and my personal curiosity, I am constantly looking for new ways of improving my skills. I am used to work in team interacting with designers and engineers. I love following new web technologies and play with them.
If you ask me what languages and tools I have used since I felt in love with web development, I will probably start with HTML4, CSS2 and PHP. However, keeping that list up to date would be really hard and I think that it is not what you should ask to a web developer.
The web is an incredibly dynamic environment. Each morning I wake up and, right during breakfast, I start looking for new technologies, articles and tools released the day before. I look for something new to learn. This is one of my key strength: the willing to learn something new every day.
These are the constants that each front-end developer should know because tools will not do that job for you. Tools and pre-compiled languages will help you code faster, not better.