arguments.length bug (not critical, but good to know)

[espruino-discuss]

Posted at 2018-01-26 by mrQ

my test snippet:

function abc(p1){
console.log(arguments.length);
}

these tests are fine:

abc(4);     // prints "1" .. ok
abc(4,5,8); // prints "3" .. ok

and here is the flaw:

abc();     // prints "1" .. NOK - "0" expected (checked on browsers and node.js)

as already mentioned - it's not critical, but some libraries written for node may fail in their arguments check.

[espruino-discuss]

Posted at 2018-01-26 by mrQ

found in 1v95 on EspruinoWIFI

[gfwilliams]

Posted at 2018-01-26 by @gfwilliams

Thanks for letting me know! I put a bug in for it here: espruino/Espruino#1321

You probably gathered already but it's because you specified an argument p1. Espruino doesn't keep a second arguments array for the sake of saving memory, so it reconstructs the array when you ask for it.

I think probably the sensible option for now is just to document this difference in the reference for arguments?

I guess there should probably be a page for known differences to the ES5 spec, like the newline handling and lack of unicode

[espruino-discuss]

Posted at 2018-01-26 by mrQ

at least some hint in the API doc (http://www.espruino.com/Reference#l__global_arguments) would be fine.

[gfwilliams]

Posted at 2018-01-29 by @gfwilliams

Just done!