In a wok or large skillet over high heat, warm the oil. Add the onion and cook, stirring frequently, for 1 minute. Stir in the garlic, then add the eggs and cook for 30 seconds, continuing to stir. Add the chicken and sauce, stirring and cooking until the chicken is no longer pink, about 8 minutes. Add the noodles and cook until warmed through, about 3 minutes.