JavaScript if/else 语句让用户输入一个值

Question

如何使 if/else 语句循环回到开头以获取用户信息？

这是我到目前为止得到的代码:

var age = prompt("Please enter your age");

if(age == 21 ) {
    alert("Happy 21st Birthday!");
} else if (age > 21 ) {
    alert("You are old");
} else { 
    alert("Please enter an age");
}

我试图让它回到开头，让用户输入信息。

Answer 1

var age = '';
while(age == '' || age == 'ok'){   
   age = prompt("Please enter your age");
   if($.isNumeric(age) === false){
       continue;
   }
   if(age == 21 ){
        alert("Happy 21st Birthday!");
        continue;
   }
   if (age > 21 ){
        alert("You are old");
        continue;
   }
   if (age < 21){ 
       alert("You are too young to be in this bar!");  
   }
}