Why do multiple plus operators parse?

Question

I don't understand why the following javascript parses; what's going on?

var a = 0;
var b = 0;
console.log(a + + + + + + + b);
console.log(a);
console.log(b);

In addition, when it does parse I'd at least expect one of a or b to be incremented, but they are not.

Output (Chrome):

0
0
0

0
0
0

Answer 1

No, the increment way is with a++ .

That you make here is to changing the sign of the number, but we know that + don't change the sign (opposite to - ). So in this:

 console.log(a + + + + + + + b);

You are saying:

a + (+ (+ (+ (+ b) ) ) )

So you are not changing the sign nor incrementing the numbers. Check this:

 console.log(a++ + + + + + + + b);

You'll obtain an increment in a variable. Output:

 0
 1
 0

Answer 2

Javascript has an unary plus operator, so this expression is essentially the same as

console.log(a + (+ (+ (+ (+ (+ (+ b)))))));

which is just, eventually, equivalent to

console.log(a + b);

Note that the increment operator, ++ (be it a prefix or postfix operator) cannot have a whitespace between the + s.