Non-canonical form does not consistently parse fractions (Rational vs. Divide)

Either I don’t understand how this is supposed to work, or there is a bug here. Canonical form is explained in the documentation. The example shown is:

ce.parse("\\frac{3}{-5}")
// ➔ ["Rational", -3, 5]

ce.parse("\\frac{3}{-5}", {canonical: false})
// ➔ ["Divide", 3, -5]

However, it doesn’t really seem like setting canonical to false really does anything. Rather, it seems that fractions with positive numerators and denominators are parsed as Rational while putting anything else in the numerator and denominator (including simply adding a -) will result in a Divide.

Example in this CodePen:

Sod the question is two-fold:

1. Does setting {canonical:false} do anything in this context? I can’t seem to get it to work.
2. Aren’t fractions supposed to be interpreted as Divide rather than Rational in the non-canonical parsing mode?

Thanks @arnog!

[MatousAc]

Thanks. Yeah, I think I understand that better now. I’m kinda new to issues (all of mine so far have been interactions with you) so thanks for your patience.

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I tried your suggestion and that worked. Thank you so much!

[arnog]

The CodePen could be more useful if it demonstrated what the problem you are talking about is. It’s a fairly generic code that doesn’t demonstrate specifically the problem (I still have to know what I’m supposed to type in the field in order to see what the problem is), and it includes a lot of things that are not necessary to demonstrate the issue (some CSS, some UI, some event handling).

Since you ask, here’s what would have made it easier:

When executing:

console.log(ce.parse('\\frac{3}{4}', { canonical: false }).toJSON());

I get ["Rational", 3, 4]. I was expecting ["Divide", 3, 4] instead since canonical is false.

This is code that I can copy and paste to verify I get the same result, and I can clearly see what you are getting vs what you are expecting.

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That said, to answer you question, if you want to avoid Rational in the json output, you can use this:

ce.jsonSerializationOptions = { exclude: ['Rational'] };
console.log(ce.parse('\\frac{3}{4}', { canonical: false }).toJSON());
// -> ["Divide", 3, 4]

The exclude JSON serialization option can be used to indicate identifiers that should be avoided and replaced by an equivalent form when possible. In this case, Rational will be replaced with a Divide.