Tom Insam

uneval() does not produce JSON

More playing with JSON and Spidermonkey has revealed yet another incredibly annoying fact (I hate those guys). Spidermonkey provides a lovely uneval() function, that does the exact opposite of eval() - turns JS objects into strings. It works on almost everything, and make life very very nice. There’s also Object.toSource() which does something similar (but not the same - try uneval("") vs "".toSource()).

But the strings that uneval produce are not valid JSON, as I have been assuming. I’ve been getting steadily more worked up at all the JSON parsers in the world, refusing to parse things that are clearly valid JavaScript, and eventually I go look at the spec, which fails to list ' as a valid string delimiter. And guess what delimiter uneval produces? Yay. So all the parsers are fine, and it’s just SpiderMonkey that’s broken.

Fortunately, Mochikit provides a nice serializeJSON() function.