I work in a large group of Java web app developers and we, of course, insist on descriptive variable names in our Java code. Many of my coworkers assume that this naming standard applies for all of the languages in our stack. But my opinion is that because almost all js variables are local - and their complete lifespan can be viewed within a single block - using brief names not just acceptable, but preferable, as it reduces noise. By the nature of functional code, the variable's significance usually is internal to the function, or to the larger mathematical context, rather than to the business concept reflected by the program's design.
The variable name's significance is so you know exactly what is going on without guessing what "foo" "bar" "count" is. I think it is more important in JavScript to have good names since the variables are loosely typed.
Who cares how long the names are. If you are worried about bytes, that is what Google Closure and other compressors are for.
Yeah I'm fine with abbreviating a local integer variable to i, a local string variable to s, a length to len, an object to obj, an event parameter to e and an entire library namespace to $, but don't go using TXTSPK in polite company