A range slider takes an input value and maps it to a point between two values, for example between 0 and 1. Typically this is done using a linear mapping, but sometimes certain areas of the range are more important than others.
Such a case might warrant allowing that important range to occupy a disproportionate amount of space on the slider. This would allow users interact with certain areas on a more fine grained level.
We could instead return the logarithm of the input value,
Two sliders control the opacity of the black rectangle. The first slider uses a logarithmic scale, the second uses the traditional linear scale.
Notice the difference in using the two sliders. In this case, a log scale is a more natural fit for the variable being manipulated (the opacity).
The human perceptual system sometimes is sensative to the logarithm of the intensity of a certain stimulus, rather than the intensity iteslf. The standard unit for measuring sound, the decibel, is logarithmic as well.
An example implementation of this idea in React follows.
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