If the basketball hits the top edge of the backboard, does it count as a foul ball?

Only what the third floor said is correct. Others are incomplete or wrong.

The backboard has six sides:

Front, reverse (back)

Left side, right side

Above (top surface), below (bottom surface)

FIBA basketball rules stipulate that the basketball only goes out of bounds if it touches the back of the backboard. In other words, the back (reverse) side of the backboard is out of bounds. The other five sides are all in bounds. Of course, the basketball does not go out of bounds when it touches the top (top) side of the backboard. This also includes the four sides that make up the top (top) side, which are all in bounds.

It should be noted that the reverse (back) side of the backboard only refers to the plane, and it does not include the four sides that make up this plane. Therefore, when the ball touches the four edges on the back but does not touch the flat surface, the ball has not yet gone out of bounds. Rather than the direction in which the ball falls, as some claim, it determines whether the ball goes out of bounds (this is a big joke).