Put your foot inside the boots of an expert developer that is new to web development.
Certainly he will must deal with JavaScript and probably he will encounter a bit of difficulties with choosing a framework for its job.
For general purpose: which one do you suggest if the an easy usage is the first requirements?
I’ve worked with jQuery, script.aculo.us, and mootools, and I would highly recommend jQuery, which seems to trump a lot of the other frameworks in its ease of use.
For someone who is familiar with HTML and CSS, jQuery fits the paradigm really well, and makes the transition into Javascript very simple.
For example, with html such as this:
You might have CSS selectors that looked like this:
In jQuery, you can manipulate those elements using the same selectors:
jQuery also has excellent documentation that can really help a beginner jump right in.