Function to interpolate between two numbers. If both start and end are numbers, it calculates the interpolated value based on the parameter animationElapsedTime (0 to 1). If either start or end is not a number, it returns the end value directly.

You will typically use this function when implementing custom animations.

animationElapsedTime can be outside the (0, 1) range, depending on easing.

This one interpolates only numbers; if you want to interpolate colors or strings then perhaps see d3-interpolate.

Available since Recharts 3.9