Use the checkAgeForm function to validate the form when the user clicks "submit". Given:
function checkAgeForm(event) {
let form = document. getElementById("userForm");
let userAge = form. userAge;

userAge. style. backgroundColor = "LightGreen";
if (userAge. value < 0) {
userAge. style. backgroundColor = "Orange";
event. preventDefault();
}
}

/* Your solution goes here */