paper-slider -- immediateValue property duplicates value property

[kenmoore]

I suspect there's something I'm missing, but the value property of a paper-slider reflects the current slider value, and can be set to apply a new value. What is the need for the immediateValue property? If there's a case for it, please make note of it in the documentation.

[David-Mulder]

Try dragging and log the two attributes ;-)

[kenmoore]

Thanks for the hint, here are some observations:

• I wasn't able to get oninput event to trigger, should it? instead I was logging the value in onchange
• when the slider is changed, immediateValue always shows the resultant new value shown by the control
• if the slider's change is enacted by a click on the slider track rather than dragging the thumb, the value property is not updated at the time the change event is fired, rather it reflects the prior value.

I'd say:

• it's counter-intuitive that value would not show the new updated slider value at onchange time if the user clicked the track vs dragged the thumb
• the docs page for paper-slider could do a much better job of explaining immediateValue and why this apparently redundant property needs to exist (currently says "The immediate value of the slider. This value is updated while the user is dragging the slider.")

[David-Mulder]

Well, once I found the docs I thought it was pretty clear, but believe me, it confused me a lot as well. And regarding on-input, check #30

[kenmoore]

I'm still unclear on whether there's a good reason not to architect the element such that the 'value' property always shows the value that the slider's position matches (whether idle, during drag, or upon click), and you could do away with the mostly (but peculiarly not always) redundant property immediateValue?

[David-Mulder]

I don't know this officially, but I suppose the 'problem' this solves is that polymer applications aren't that event driven, normally you observe for changes to properties, not for actual events. And now you have a choice how that binding should behave. Not necessarily defending this choice, just rationalizing it.

[grigio]

:+1 Shouldn't <paper-slider> fire an event from immediateValueChanged ? I'm trying to get the value while the user is dragging the marker but it doesn't seem to be working as advertised https://github.com/Polymer/paper-slider/blob/master/paper-slider.html#L178-L185

[David-Mulder]

@grigio Did you polymer bind it to the value of immediateValue?

[grigio]

I tried but it seems to work like changed event

[David-Mulder]

@grigio Try taking a look at this code, I got it working there, but it's been a couple of weeks since then~