Uncaught SyntaxError: Got ?[198] expected ID

[espruino-discuss]

Posted at 2021-09-06 by Robin

Mon 2021.09.06

During development, attempted to create shortened two letter function names that maintained alignment.

Significantly shortened statement:

function of() { }

Throws error:

Uncaught SyntaxError: Got ?[198] expected ID

There is no immediate rush to resolve this for me as I've created a temporary workaround. More curious as to what is causing this.

>process.env
={
  VERSION: "2v00",
  GIT_COMMIT: "ff35517",
  BOARD: "ESP8266_4MB",
  FLASH: 0, RAM: 81920,
  MODULES: "Flash,Storage,hea" ... "r,crypto,neopixel",

of is not a reserved word:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#reserved_keywords_as_of_ecmascript_2015

However, I did find a reference used within a for loop:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of

I'm making the assumption that 'of' might be parsed as part of the statement syntax in this case, but really doesn't answer why a function may not have the same name as it isn't a reserved keyword.

[gfwilliams]

Posted at 2021-09-14 by @gfwilliams

Thanks! In Espruino, of is a reserved word because of for (var i of foo) so I'm surprised it's actually not in the JS spec.

I'd been having issues with the Layout.js file when pretokenised, so it's actually possible you're having the same issue. I just filed a bug for this so I can track it espruino/Espruino#2047

This particular one should be an easy fix (changing the pretokeniser to ignore 'of') but there are definitely other cases like this where it could be a problem.

[gfwilliams]

Posted at 2021-09-16 by @gfwilliams

Turns out the pretokeniser issue is unrelated, so this issue is very specifically just if you decide to call a function of.