Boa: Implement `Number.prototype.toPrecision`

[HalidOdat]

The toPrecision() method returns a string representing the Number object to the specified precision.

More information:

• MDN documentation
• ECMAScript reference

[zanayr]

I think I can handle this. :)

I assume it'll live in number/mod.rs?

[HalidOdat]

I assume it'll live in number/mod.rs?

Yes. There already is the to_precision function but its not implemented here

[zanayr]

Hello, I'm finally moving on this, sorry for the delay. I understand what we are trying to do with toPercision, but I have a few questions concerning the ECMA documentation:

1. In step 9.a, "let e and n..." I'm going to need a resource on this math.. I understand some of it, but I'm not really familiar with range math? If you know of what I can reference to understand it better, I would be grateful!
2. In step 9.b, "let m be the String..." Does that me something like: '.0001'?
3. In step 9.c.ii.1, "Let a be the first code unit..." I assume they mean the 0x value for whatever character is first in m?

Thanks! Best,

[zanayr]

Actually I think I just figured out #1. It's just a fancy way of saying n * 10^(e - p + 1) - x
The other questions still stand, but I think my assumptions are correct with those as well.

Best,

[HalidOdat]

Hi @zanayr

Maybe checking other engines implementation will help:
V8: https://github.com/v8/v8/blob/4b9b23521e6fd42373ebbcb20ebe03bf445494f9/src/conversions.cc#L1159-L1225
SpiderMonkey: https://searchfox.org/mozilla-central/source/mfbt/double-conversion/double-conversion/double-to-string.cc#296-353

Hope this helps :)

[Razican]

Hello @zanayr, how is this going?

[zanayr]

Hello @zanayr, how is this going?

Hello @Razican, Apologies I have been extremely busy and this slipped my mind. I think I left off somewhere still trying to figure out the math behind 9a. I don't know if I can figure it out, perhaps I should've picked an easier issue. 😅

[Razican]

Hello @zanayr, how is this going?

Hello @Razican, Apologies I have been extremely busy and this slipped my mind. I think I left off somewhere still trying to figure out the math behind 9a. I don't know if I can figure it out, perhaps I should've picked an easier issue. sweat_smile

Would you like us to un-assign it from you? Or would you like to create a draft PR to get some feedback / help?

[zanayr]

Hello @zanayr, how is this going?

Hello @Razican, Apologies I have been extremely busy and this slipped my mind. I think I left off somewhere still trying to figure out the math behind 9a. I don't know if I can figure it out, perhaps I should've picked an easier issue. sweat_smile

Would you like us to un-assign it from you? Or would you like to create a draft PR to get some feedback / help?

I probably should be un-assigned, I don't have the bandwidth to work on it right now, and I didn't really get that far to begin with. Apologies again, as soon as I am more free, I will return for to help on this project.

[NathanRoyer]

Hey ! I'm currently working on this.