js: reference(s)
- built-in(s) -- array, date, math, number, string, ...
- function(s) -- function name( args ) { ... }
- event(s) -- onload, mouse, key, timer
- variable(s) -- var x = expression
- constructor(s) -- function object() { attribute: value; }
closure(s) -- x = function () { ... }
meta-programming -- x = eval(string)
object(s) -- window, navigator, screen, ..., document