js表格验证电台

Question

我试图逐步完成表格，在＆＃34; tab＆＃34;我只有收音机按钮，我想无法继续前进，直到他们中的一个人没有被选中这样的代码：

var currentTab = 0; // Current tab is set to be the first tab (0)
showTab(currentTab); // Display the current tab

function showTab(n) {
    // This function will display the specified tab of the form ...
    var x = document.getElementsByClassName("tab");
    x[n].style.display = "block";
    // ... and fix the Previous/Next buttons:
    if (n > 0) {
        document.getElementById("prevBtn").style.display = "inline";
        document.getElementById('submBtn').style.display = "none";
    } else {
        document.getElementById("prevBtn").style.display = "none";
        document.getElementById('submBtn').style.display = "none";
        document.getElementById("nextBtn").style.display = "inline";
    }
    if (n == (x.length - 1)) {
        document.getElementById("nextBtn").style.display = "none";
        document.getElementById('submBtn').style.display = "inline";

    } else {
        document.getElementById("nextBtn").InnerHTML = "Next";
    }
    // ... and run a function that displays the correct step indicator:
    fixStepIndicator(n)
}

   function validateForm() {
    // This function deals with validation of the form fields
    var x, y, i, valid = true;
    x = document.getElementsByClassName("tab");
    y = x[currentTab].getElementsByTagName("input");

    // A loop that checks every input field in the current tab:
    for (i = 0; i < y.length; i++) {
        // If a field is empty...
        if (y[i].value == "" || getElementsByTagName("selector").prop('checked', true)) {
            // add an "invalid" class to the field:
            y[i].className += " invalid";
            // and set the current valid status to false:
            valid = false;
        }
    }
    // If the valid status is true, mark the step as finished and valid:
    if (valid) {
        document.getElementsByClassName("step")[currentTab].className += " finish";
    }
    return valid; // return the valid status
}

单选按钮的名称是＆＃34;选择器＆＃34;，我已尝试按标签名称，按类型，按类别，按ID调用它们，尝试检查是否已选中通过函数prop（），以及 name .checked == true的ckeck状态，它不起作用; /任何sugestions？ ：）