What does console.log('b' + 'a' + + 'a' + 'a') output?

Console output

Why

The doubled "+ +" is a binary plus followed by a unary plus. The unary + applies to "a", attempting numeric conversion, which fails and yields NaN. Building left to right: "b"+"a" = "ba", then "ba" + NaN concatenates to "baNaN", and the final + "a" gives "baNaNa". A delicious accident of operator parsing.