如何确保在提交多页表单之前至少选中了一个复选框？

Question

我正在处理一个包含多个页面的表单。 在一个页面上，我有复选框，我需要在提交前至少选择一个。 我怎么能用javascript / html5做到这一点，这是我的小提琴

这是用javascript更改页面的所有形式。 如果至少选中了一个复选框，我可以在最后一页上检查表格吗？ 请高级指教，感谢您的帮助！

 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> 

Answer 1

这是一个对至少一个复选框进行验证的页面。

 <html> <head> <script> var checkbox = document.querySelector("input[name=checkbox]"); function mFunction (e) { if(![...document.querySelectorAll("input[type='checkbox']")].some(i=>i.checked)) { alert('not checked'); e.preventDefault(); } }; function checkForm(t,e) { e.preventDefault(); console.log('checked'); }; //another way to check if check box checked -check! // function mFunction () { // let matches = document.querySelectorAll('input[type=checkbox]:checked'); // if (matches.length < 1) { // alert('not checked'); // return false; // } // }; </script> </head> <body> <!-- <form> <input type="checkbox" name="choice1" value="choice1" id="confirm">choice 1<br> <input type="checkbox" name="choice2" value="choice2" >choice 2<br> <input type="checkbox" name="choice3" value="choice3">choice 3<br><br> <input type="submit" value="Submit" onclick="mFunction()"> </form> --> <form onsubmit="checkForm(this,event);"> <input type="checkbox" name="choice1" value="choice1" id="confirm">choice 1<br> <input type="checkbox" name="choice2" value="choice2" >choice 2<br> <input type="checkbox" name="choice3" value="choice3">choice 3<br><br> <input type="submit" value="Submit" onclick="mFunction(event)"> </form> </html> 

Answer 2

在验证功能中，首先检查当前选项卡是否有任何复选框。 如果是，请检查是否至少检查了其中一个。 如果不是，请设置valid = false

 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; } } // Are there any checkboxes on the current page? if (x[currentTab].querySelector("input[type=checkbox]")) { // Is at least one of them checked? if (!x[currentTab].querySelector("input[type=checkbox]:checked")) { 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 }