javascript - 取id值

Question

我想获取下面内容的id值？

<form id="mainForm"  name="mainForm">
    <input type="radio" id="4" name="rads" value="1" checked>
    <input type="radio" id="3" name="rads" value="2" />
    <input type="radio" id="2" name="rads" value="3" />
    <input type="radio" id="1" name="rads" value="4" />
</form>
<span id="result"></span>
<span id="test"></span>

<script>
    document.mainForm.onclick = function(){
        var radVal = document.mainForm.rads.value;
        var idVal = document.getElementsById('id');
        result.innerHTML = 'You selected: '+radVal;
        test.innerHTML = 'You id: '+idVal;
    }
</script>

您选择的值:1您选择的 ID:4

Answer 1

你应该这样做

document.mainForm.onclick = function(){
        var radVal = document.mainForm.rads.value;
        var idVal = document.querySelector('[name="rads"]:checked').id;
        result.innerHTML = 'You selected: '+radVal;
        test.innerHTML = 'You id: '+idVal;
    }

您需要使用 document.querySelector('[name="rads"]:checked') 选择选中的元素，然后使用 .id 获取 id