您可以使用 break 语句。例如：

You can return from while loop with break statement. For example:

var userAge = prompt("Please enter your age");
while (true) {
    if (isNaN(userAge)) {
        alert("That's not a number, please retry.");
    } else if (userAge < 0 || userAge >= 200) {
        alert("I think you may be lying about your age.");
    } else {
        break;
    }
    var userAge = prompt("Please re-enter your age.");
}
if (userAge == 0) {
    alert("So you're a baby!");
} else {
    alert("That's a good age.");
}