The ornamental design for a handle for juice and milk cartons, as shown and described.
FIG. 1 is a perspective view of a handle for juice and milk cartons showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left side elevational view thereof, the right side elevational view being a mirror image thereof;
FIG. 4 is a top elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a bottom elevational view thereof; and,
FIG. 7 is a perspective view showing the handle for juice and milk cartons in use; the broken lines depict environmental structure for illustrative purposes only and form no part of the claimed design.