Preheat oven to 350°F.
Grease a 9x13-inch baking pan with nonstick cooking spray.
In a large bowl, combine the flour, pineapple (with juices), sugar, eggs, vanilla, baking soda, and salt and stir until well combined.
Pour the cake batter into the prepared baking pan and bake until a toothpick inserted in the center comes out clean, 35 to 40 minutes.
Meanwhile, make the topping. In a small saucepan, combine the butter, evaporated milk, and sugar. Cook over medium heat and stir until the butter is melted and the sugar has dissolved, about 3 minutes.
Remove from heat and stir in the coconut, pecans, and salt.
Once the cake comes out of the oven, use a chopstick to poke holes all over the cake. While the cake is still warm, pour the topping over the cake and use a spoon to spread it evenly over the top. Allow to cool or serve warm.
Store leftover cake, wrapped in plastic wrap, in the refrigerator for 3 to 4 days. Allow to come to room temperature before serving.
