Season the chicken with salt, and set aside.
To make the sauce, whisk sugars with ketchup, soy sauce, pineapple juice, and vinegar in a bowl.
Add about 2 inches of oil to a heavy-bottomed Dutch oven and preheat it while you prep the rest of the ingredients. The oil must reach 350°F (180°C).
Take three shallow bowls, add cornstarch to one, eggs to another, and flour to the third one.
Toss the chicken in the cornstarch, dip in egg, and toss again in flour.
Drop the chicken in hot oil and fry for 2-3 minutes or until lightly browed and crispy. Remove with a strainer onto a wire rack. Work in batches, and repeat with the rest of the chicken.
Add 1 tablespoon of oil (take it from the frying oil) to a skillet over medium-high heat, the onions, and the bell peppers, and cook for 3 minutes until slightly softened but crisp (crisp tender).
Add the pineapple chunks, and the sauce ingredients and cook for 2 minutes or until the sauce has thickened.
Add the crispy chicken, and coat in the sauce. Add the garlic, fold it in, and remove from heat immediately. Serve over cooked jasmine rice.