Javascript “tuple” notation: what is its point?

Question

At wtfjs, I found that the following is legal javascript.

\",,,\" == Array((null,\'cool\',false,NaN,4)); // true

The argument (null,\

Answer 1

You are seeing the effect of the comma operator.

The comma operator evaluates both of its operands (from left to right) and returns the value of the second operand.

The resultant value when a,b,c,...,n is evaluated will always be the value of the rightmost expression, however all expressions in the chain are still evaluated (from left to right).