Check if checkbox is checked before submit

Question

I have form with steps. On last step I have to send form to another page. On my script, I have checked inputs and select. But how can I add a check if checkbox is checked, and if not checked restrict sending?

I am trying this:

<form id="regForm" method="POST" action="my action">
<div class="tab">FIRST Tab</div>
<div class="tab">END TAB BEFORE SUBMIT
<input placeholder="Name" oninput="this.className = ''" name="first_name" value="">
<input placeholder="Last Name" oninput="this.className = ''" name="first_name" value="">
<label id="chkbx"><font color="red">Yes</font>, OK TEST
    <input type="checkbox" oninput="this.className = ''"></label>

</div>

BUTTONS NEXT AND PREVIUS ON LAST PAGE CHANGE NEXT BUTTON TO SUBMIT 
 <button type="button" class="button-base button-blue wow animated" data-wow-duration="2s" data-wow-delay="0s" data-wow-iteration="10" id="prevBtn" onclick="nextPrev(-1)">Назад</button>
    <button type="button" class="button-base button-blue wow animated" data-wow-duration="2s" data-wow-delay="0s" data-wow-iteration="10" id="nextBtn" onclick="nextPrev(1)"><i class="fas fa-cart-plus"></i> Продължете с поръчката</button>

</form>

And my javascript used for everything like change tab, submit tab, check tab...

<script>
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 = "Към плащане";
  } else {
    document.getElementById("nextBtn").innerHTML = "<i class='fas fa-cart-plus'></i> Продължете с поръчката";
  }
  // ... and run a function that displays 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, b, y, n, i, valid = true;
  x = document.getElementsByClassName("tab");
  y = x[currentTab].getElementsByTagName("input");
  n = x[currentTab].getElementsByTagName("select");
  // 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;
    }
  }
  for (i = 0; i < n.length; i++) {
    // If a field is empty...
    if (n[i].value == "") {
      // add an "invalid" class to the field:
      n[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 to the current step:
  x[n].className += " active";
}

Answer 1

 <input type="checkbox" oninput="this.className = ''"></label>

Add id field in the checkbox

   <input type="checkbox" id="checkBoxId" oninput="this.className = ''"></label>

You can verify check box is checked before form submit.

document.getElementById("regForm").submit();

Replace this line by the following

if(document.getElementById('checkBoxId').is(':checked')){
    document.getElementById("regForm").submit();
}else{
//anything you want
}

Answer 2

You can follow this code and instructions:

first, you call a function in submit

<FORM NAME="myForm" onSubmit="return yourFunction()">

Check the checkbox is checked by using jquery

function yourFunction(e) {
  e.stopPropagation();
  e.preventDefault();
  return ($('#mycheck').is(':checked'));
}

when the checkbox is checked then approve submit otherwise not submit

2nd process is

 $('#myform').on('submit', function(event) { event.preventDefault(); event.stopPropagation(); ($('#mycheck').is(':checked'))?console.log('submit allow') : console.log('Not allow submit'); return ($('#mycheck').is(':checked')); }); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <form action="#" id="myform"> <input type="text" > <input type="checkbox" id="mycheck"> <button>submit</button> </form> 

== Thanks ==

Answer 3

HTML code:

<form action="./addUser.htm" onsubmit='return myfunction();' method="POST" autocomplete="off">

<input type="checkbox" id="ABC" name="ParamList" class="clonecheckbox" value="ABC"> ABC
<input type="checkbox" id="PQR" name="ParamList" class="clonecheckbox" value="PQR"> PQR
<input type="checkbox" id="XYZ" name="ParamList" class="clonecheckbox" value="XYZ"> XYZ
...
...
...
...

    <input class="btn btn-outline-success" type="submit" value="Add " id="adduser" />           

</form>

JS code:

For any one of them

function myfunction() {

  var selectedCheckbox = $('input:checkbox:checked.clonecheckbox').map(function () {
          return this.value;
        }).get(); 

    if($('.clonecheckbox:checked').length == 0) {
         return false;
    } else {
        return true;
    }

 }

OR

For single ckeckBox using Jquery

 if ($('#ABC').prop("checked")) {
        return true;
  }else{
       return false;
}
// OR
if($('#ABC').prop("checked") == true){
         return true;
   }else{
         return false;
}