Tooltip value display incorrent

[hatienloi]

Step

• Add new chart with x: [1,2,3,4,5], y: [2.02825,1.63728,171.96,4.8485,4.73463],and hovertemplate: '<i>Price</i>: $%{y:.1f}',
• Check display when hover to point.

Codesandbox
https://codesandbox.io/p/sandbox/plotlyjs-issue-9zd9rk?file=%2Findex.html

Screenshots

• With 171..95 => Incorrect
  

• With 171.96 => Correct
  

[alexcjohnson]

Interesting, thanks @hatienloi!

I suspect this is due to the fact that with JS floating point, 171.95 actually IS closer to 171.9 than to 172.0:

> 171.95-171
0.9499999999999886

And if so it's going to be tough to fix without breaking numbers that are just a little bit lower, like 171.949999, so really SHOULD round down.

If anyone is interested in taking a crack at this, it will be crucial to add good unit tests

[hatienloi]

Interesting, thanks @hatienloi!

I suspect this is due to the fact that with JS floating point, 171.95 actually IS closer to 171.9 than to 172.0:

> 171.95-171
0.9499999999999886

And if so it's going to be tough to fix without breaking numbers that are just a little bit lower, like 171.949999, so really SHOULD round down.

If anyone is interested in taking a crack at this, it will be crucial to add good unit tests

@alexcjohnson Yes, so weird. Could we have a fix for it

[archmoj]

Thanks for the report.
Please provide a link to your codepen in the issue description.

[hatienloi]

@archmoj Updated the description with codesandbox link. Thanks!

[archmoj]

@archmoj Updated the description with codesandbox link. Thanks!

Please note the "latest" bundle you are using is last v1.
In this codepen I use latest v2 plotly.js and I get 172.0 in the hover. Do you get the same number?

[hatienloi]

@archmoj Updated the description with codesandbox link. Thanks!

Please note the "latest" bundle you are using is last v1. In this codepen I use latest v2 plotly.js and I get 172.0 in the hover. Do you get the same number?

@archmoj With 171.9599999 i got the same number like you. But with 171.95 it stills 171.9

[hatienloi]

Hi @archmoj Any update for it? Do we have a patch fix for it?