我正在处理具有多个页面的表单。在一页上，我有复选框，要求至少在提交之前选中一个复选框。如何使用javascript / html5做到这一点，这是我的小提琴
这是用javascript更改页面的全部一种形式。如何在最后一页上检查是否已至少选中一个复选框？请并且感谢您对高级的任何帮助！
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 = "none";
} else {
document.getElementById("prevBtn").style.display = "inline";
}
if (n == (x.length - 1)) {
document.getElementById("nextBtn").innerHTML = "Submit";
} else {
document.getElementById("nextBtn").innerHTML = "Next";
}
//... and run a function that will display the correct step indicator:
fixStepIndicator(n)
}
function nextPrev(n) {
// This function will figure out which tab to display
var x = document.getElementsByClassName("tab");
// Exit the function if any field in the current tab is invalid:
if (n == 1 && !validateForm()) return false;
// Hide the current tab:
x[currentTab].style.display = "none";
// Increase or decrease the current tab by 1:
currentTab = currentTab + n;
// if you have reached the end of the form...
if (currentTab >= x.length) {
// ... the form gets submitted:
document.getElementById("regForm").submit();
return false;
}
// Otherwise, display the correct tab:
showTab(currentTab);
}
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 == "") {
// 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
}
function fixStepIndicator(n) {
// This function removes the "active" class of all steps...
var i, x = document.getElementsByClassName("step");
for (i = 0; i < x.length; i++) {
x[i].className = x[i].className.replace(" active", "");
}
//... and adds the "active" class on the current step:
x[n].className += " active";
}
* {
box-sizing: border-box;
}
body {
background-color: #f1f1f1;
}
#regForm {
background-color: #ffffff;
margin: 100px auto;
font-family: Raleway;
padding: 40px;
width: 70%;
min-width: 300px;
}
h1 {
text-align: center;
}
input {
padding: 10px;
width: 100%;
font-size: 17px;
font-family: Raleway;
border: 1px solid #aaaaaa;
}
/* Mark input boxes that gets an error on validation: */
input.invalid {
background-color: #ffdddd;
}
/* Hide all steps by default: */
.tab {
display: none;
}
button {
background-color: #4CAF50;
color: #ffffff;
border: none;
padding: 10px 20px;
font-size: 17px;
font-family: Raleway;
cursor: pointer;
}
button:hover {
opacity: 0.8;
}
#prevBtn {
background-color: #bbbbbb;
}
/* Make circles that indicate the steps of the form: */
.step {
height: 15px;
width: 15px;
margin: 0 2px;
background-color: #bbbbbb;
border: none;
border-radius: 50%;
display: inline-block;
opacity: 0.5;
}
.step.active {
opacity: 1;
}
/* Mark the steps that are finished and valid: */
.step.finish {
background-color: #4CAF50;
}
<form id="regForm" action="/action_page.php">
<h1>Register:</h1>
<!-- One "tab" for each step in the form: -->
<div class="tab">Name:
<p><input placeholder="First name..." oninput="this.className = ''" name="fname"></p>
<p><input placeholder="Last name..." oninput="this.className = ''" name="lname"></p>
</div>
<div class="tab">Contact Info:
<p><input placeholder="E-mail..." oninput="this.className = ''" name="email"></p>
<p><input placeholder="Phone..." oninput="this.className = ''" name="phone"></p>
</div>
<div class="tab">
<H3 id="subhead">AUDITORIUM ROOM SETUP & EQUIPMENT REQUESTS</H3>
<label><label id="asterisk">*</label>Room Setup (Select all that apply):</label><br><br>
<!-- <p><input placeholder="dd" oninput="this.className = ''" name="dd"></p> -->
<br>
<input id="element_3_1" name="Room-Setup" required type="checkbox" value="Auditorium-Seating-for-300" />
<label class="choice" id="labelinput" for="element_3_1">Auditorium Seating for 300</label>
<br>
<input id="element_3_2" name="Room-Setup" class="elementcheckbox" type="checkbox" value="Auditorium-Seating-for-350" />
<label class="choice" id="labelinput" for="element_3_2">Auditorium Seating for 350 (recommended max for Performances</label>
<label class="choice" for="element_3_3">Auditorium Seating 400</label>
<input id="element_3_3" name="Room-Setup" class="elementcheckbox" type="checkbox" value="Auditorium-Seating-400" />
<label class="choice" for="element_3_4">Round Tables and Chairs</label>
<input id="element_3_4" name="Room-Setup" class="elementcheckbox" type="checkbox" value="Round-Tables-and-Chairs" />
<label class="choice" for="element_3_5">Other (Please note that we cannot change the auditorium setup during your event*)</label>
<input id="element_3_5" name="Room-Setup" class="elementcheckbox" type="checkbox" value="Other" />
</div>
<div style="overflow:auto;">
<div style="float:right;">
<button type="button" id="prevBtn" onclick="nextPrev(-1)">Previous</button>
<button type="button" id="nextBtn" onclick="nextPrev(1)">Next</button>
</div>
</div>
<!-- Circles which indicates the steps of the form: -->
<div style="text-align:center;margin-top:40px;">
<span class="step"></span>
<span class="step"></span>
<span class="step"></span>
<span class="step"></span>
</div>
</form>
答案 0 :(得分：1)
在<div class="tab theFirstTabWithCheckboxes">中输入第二个类名
此代码获取该元素并计算cheched对全局变量的输入
var checkboxes = document.querySelectorAll("tab.theFirstTabWithCheckboxes input");
var i = checkboxes.length;
window.count_nr_of_checked_boxes = 0;
while (i--) { //count down to 0
if (checkboxes[i].checked) window.count_nr_of_checked_boxes++;
}
使用querySelectorAll()进行选择的方式与在CSS中选择方式相同。请注意the dot operator is an and operator和空格运算符如何表示“输入在内部...”（从右到左求值）。
将以下行放入函数validateForm（）
if (count_nr_of_checked_boxes < 1) valid = false
您不需要在全局变量上使用window.