There is no direct driving route from Dallas, Texas to the Pacific Ocean because Dallas is ~1,300 miles (2,100 km) inland. The Pacific coast is in California, Oregon, Washington—reached only by crossing the entire southwestern US.
Because the Pacific Ocean is a coastline, not a point. Distance depends entirely on which coastal destination you choose. The original answer correctly noted Dallas is inland but oversimplified by saying "no accurate driving distance"—there are many accurate distances, just no *single* one.
Dallas is a Gulf of Mexico / Atlantic watershed city (Trinity River → Galveston Bay). To reach the Pacific, you cross the Continental Divide in New Mexico/Arizona.