napi_is_function

[jorangreef]

I have looked through all the documentation, but there doesn't seem to be a way to verify that a napi_value is a JS function, e.g. using something like napi_is_function?

The reason for asking, is that I need to verify all user-supplied arguments (including a JS callback) and throw an exception before queuing async work.

[jorangreef]

I just came across napi_function which can be used like this:

napi_valuetype type;
assert(napi_typeof(env, argv[0], &type) == napi_ok);
if (type != napi_function) {}

[gabrielschulhof]

@jorangreef yep, that's the way to ascertain whether a napi_value holds one of the primitive types + napi_external 🙂

[ralphtheninja]

@jorangreef Check out napi-macros module by @mafintosh. There might be some handy stuff for you in there. Also, maybe add a NAPI_ARGV_FUNCTION() which does this assertion?

[jorangreef]

Thanks @gabrielschulhof and @ralphtheninja