Weird API logging issue...

So... this is quite annoying and was pissing me off as I was trying to work on updating a script. Why does it do this? log (parseInt("a")); // Logs as null log ("" + parseInt("a")); // Logs as NaN

Because parseInt("a") is NaN (which, it seems, is logged as null), while "" + parseInt("a") converts the number parseInt("a") (i.e. NaN) to a string, so it is the the string "NaN".That is, what you have is the same as: log(NaN); // logged as null log("NaN"); // logged as NaN The only thing that's really strange here is the NaN logs as null...

Our best guess at the implementation of log() is something like: const log = function(thing){ if(_.isString(thing)){ return console.write(thing); } return console.write(JSON.stringify(thing)); }; JSON doesn't have a representation for NaN.  In the first case, it gets converted to null as the "not a value" identifier for JSON.  In the second case, you are concatenating it with a string, causing NaN.toString() to be called, which returns "NaN".

Ah. Makes sense now. Thanks!

The Aaron said: Our best guess at the implementation of log() is something like: const log = function(thing){ if(_.isString(thing)){ return console.write(thing); } return console.write(JSON.stringify(thing)); }; JSON doesn't have a representation for NaN.  In the first case, it gets converted to null as the "not a value" identifier for JSON.  In the second case, you are concatenating it with a string, causing NaN.toString() to be called, which returns "NaN". Pretty sure the log implementation doesn't special-case strings, since the output includes quotes; JSON.stringify('a') produces "a" . Once upon a time, it was possible to look at the source code for the Roll20 library functions (eg, log(log.toString()) ), but Riley closed that after I mentioned it to him. And there I was not thinking to record anything for posterity. =P