zoom.translateBy()

zoom.translateBy(selection, x, y)

If selection is a selection, translates the current zoom transform of the selected elements by x and y, such that the new t_x1 = t_x0 + k × x and t_y1 = t_y0 + k × y. If selection is a transition, defines a “zoom” tween translating the current transform. This method is a convenience method for zoom.transform. The x and y translation amounts may be specified either as numbers or as functions that returns numbers. If a function, it is invoked for each selected element, being passed the current datum d and index i, with the this context as the current DOM element.