Adding a new parameter: _precision.

[Danjohnsonnj]

The interpolation of values could result in values with decimals of an extremely long length, e.g. 'width: 50.12345678901%'. Since scrolling causes browser repaints, which will be impacted by updated CSS values, performance can be negatively impacted.

I'm proposing a new init option: _precision. This will be used to limit the interpolated value returned from _calcInterpolation via the toFixed(n) method. The default will be 10 (which is likely more than enough for most use-cases) or the user-specified value.

[Danjohnsonnj]

The second commit (f87e217) builds upon the first by allowing a per-element override of the global precision via a 'data-precision' attribute.

[Prinzhorn]

First of all thank you for taking the time to write this patch.

I have multiple concerns:

• Can you actually measure a performance difference? If so, please provide a demo.
• Does it actually do what you intend (given the first bullet point is yes)? Let's take a simple example with some made up numbers

data-0="left:0%;"
data-800="left:55%"

now for every pixel you scroll, it moves about 0.06875% like this

0: 0%
1: 0.06875%
2: 0.1375%
3: 0.20625
......
799: 54.9312%
800: 55%

as you can see, even the first decimal place changes every pixel you scroll. This means specifying a precision between 1 and 10 does not have any effect.

• It's way too complex for most users to grasp what this option is supposed to do (it took me a while to get it and think about the implications). I don't think anybody will do anything useful with this option.

[ghost]

I think this would be a good thing to use with :before :after selectors, for example, If someone wants to show from 0% to 95.5%, they could set up something like this:

<p class='percentual' data-percent='0' data-0='@data-percent:0' data-1500='@data-percent:95.5'>
</p>

.percentual:before {
  content: attr(data-percent) "%"
}

with this we can avoid showing 10.5375%, and only show 10.53% if we want.

I don't know if there's already an easier way to do this without this modification.

[Prinzhorn]

I think this would be a good thing to use with :before :after selectors, for example, If someone wants to show from 0% to 95.5%, they could set up something like this:

That's a very interesting use-case. But I don't see this being used widely. Also attr() doesn't give you any control about formatting anyway, so it's kind of useless (e.g. in German the decimal separator is a comma 95,5%). That being said, I won't add this option just for number formatting.

[shinrox]

Yeah, I agree that's not a must have feature 😜 just said to show some use-case