javascript - 测验 - if 语句

Question

为什么选择不正确单选选项时，if语句中的else仍然出现？ else 部分只应在未选择单选按钮时出现。真正的结果是下一个问题和可能的答案出现。这是 jsfiddle .我做错了什么？

function checkAnswer(){
submit.onclick = function(){
var radios = document.getElementsByName('choices');
var i = 0;
var len = radios.length; 

    while(i<len){
        if(radios[i].checked){
            if(radios[i].id == allQuestions[0].correctAnswer){
                userScore++;
                alert("curent score:" + userScore);
                break;
            }
        }else{
            alert("Please selected an option");
            break;
        }
        i++
    }
  }
}

Answer 1

您正在遍历所有单选按钮。如果超过 1 个，则保证至少有一个未被选中，因此您将进入 else。试试这个:

function checkAnswer(){
    submit.onclick = function(){
        var radios = document.getElementsByName('choices');
        var i = 0;
        var len = radios.length; 
        var foundSelected = false;
        while(i<len){
            if(radios[i].checked){
                foundSelected = true;
                if(radios[i].id == allQuestions[0].correctAnswer){
                    userScore++;
                    alert("curent score:" + userScore);
                    break;
                }
            }
            i++
        }
        if (!foundSelected)
            alert("Please selected an option");
    }
}