[Slider] [Request] Numeric Slider Values

[smcguinness]

Description

The slider currently does not offer out-of-the-box value display. According to the Material Design Spec, there is a slider which has the current value in an element above onSlide.

Images & references

[ashl1]

It is related to #3393

[tariqwest]

@smcguinness I put together this quick solution, may be helpful for you. Considering developing it further... https://github.com/tariqwest/material-ui-slider-label

[oliviertassinari]

We plan on migrating the component to the v1-beta branch. I'm closing the issue for #4793.