point.domain()

point.domain([domain])

If domain is specified, sets the domain to the specified array of values. The first element in domain will be mapped to the first point, the second domain value to the second point, and so on. Domain values are stored internally in a map from stringified value to index; the resulting index is then used to determine the point. Thus, a point scale’s values must be coercible to a string, and the stringified version of the domain value uniquely identifies the corresponding point. If domain is not specified, this method returns the current domain.