大神求解 在线等 谢谢！

var myAge=prompt("Enter your age","");
if(myAge>=0 && myAge<=10){
document.write("myAge is between 0 and 10 ");
}
else
if(myAge >=30 && myAge<=39)||(myAge >= 80 && myAge<=89) {
document.write("myAge is between 30 and 39 "+"or myAge is between 80 and 89");
} else {
document.write("myAge is not between 0 and 10 nor is ti beteen 30 anfd 39,nor is it beteen 80 and 89");
}
插入这一段没有什么反映 也检查不出来哪里错了 希望各位大神帮忙解答一下 谢谢！！！！