continuous(value)
Given a value from the domain, returns the corresponding value from the range. If the given value is outside the domain, and clamping is not enabled, the mapping may be extrapolated such that the returned value is outside the range. For example, to apply a position encoding:
var x = d3.scaleLinear()
.domain([10, 130])
.range([0, 960]);
x(20); // 80
x(50); // 320
Or to apply a color encoding:
var color = d3.scaleLinear()
.domain([10, 100])
.range(["brown", "
