强制用户在JavaScript提示框中输入值

Question

I was wondering how to force the user to input a value into the prompt box, not leaving it empty. This is my code so far, the while loop is there to ensure that the 3 same answers are not asked.

answer1 = parseInt(prompt(question1.q1+" "+" 1. " +question1.a1+" "+" 2. "+question1.a2+" "+" 3. "+question1.a3));
        while(answer1 < 1 || answer1 > 3){
              answer1 = parseInt(prompt("Please enter a number between 1 and 3: "+question1.q1+ " "+" 1. "+question1.a1+" "+" 2. "+question1.a2+" "+" 3. "+question1.a3 ));
              }

Answer 1

As alert, prompt are dangerous as security point of view, In near future these are going to be obsolete. For now you can't force user to input the value. One possible solution is to keep displaying dialog until user put the value. But again user can stop this dialog.

function callPrompt(msg){
  tag = prompt(msg);
  if(tag == null){
     callPrompt("updated " + msg)
  }
 return tag;
 }
}
//call function to get value.
console.log(callPrompt("enter value"))