The JavaScript Comma Operator

(на русском, 日本)
 
Let’s begin with a funny tweet:

The ‘c’ at the end is for the lowly comma operator. Last in the line of operator precedence and rarely documented, the comma operator hides its light under a bushel. It may not be a JavaScript heavy-hitter but I like it anyway. Its simple, elegant and you should make it your friend. So, here we go – more than you’ll ever need to know about JavaScript’s bashful hero: