Strings. I was thinking, "Why are there twice as many backslashes!?" Then, it hit me: the output is correct! It is escaping the value of the string, just as if a programmer were to have typed it. Duh. You can use the output as-is when copy-and-pasting. No need to manually add extra backspaces! That's pretty convenient, eh? This really had me confused me at first, though, because I am so used to the behavior of Chrome's console, which prints out the unescaped string values (even though it does put quotes around the value).
$ node > "\ " ' ' > JSON.stringify("\ ") '" "' > "\\" '\\' > JSON.stringify("\\") '"\\\\"' > new Buffer("\\") <Buffer 5c> > new Buffer([0x5c]).toString() '\\' > new Buffer([0x5c, 0x5c]).toString() '\\\\'