How to Check If a Checkbox Is Checked

Check if checkbox is checked with jQuery

IDs must be unique in your document, meaning that you shouldn't do this:

<input type="checkbox" name="chk[]" id="chk[]" value="Apples" />
<input type="checkbox" name="chk[]" id="chk[]" value="Bananas" />

Instead, drop the ID, and then select them by name, or by a containing element:

<fieldset id="checkArray">
    <input type="checkbox" name="chk[]" value="Apples" />

    <input type="checkbox" name="chk[]" value="Bananas" />
</fieldset>

And now the jQuery:

var atLeastOneIsChecked = $('#checkArray:checkbox:checked').length > 0;
//there should be no space between identifier and selector

// or, without the container:

var atLeastOneIsChecked = $('input[name="chk[]"]:checked').length > 0;

How do I check whether a checkbox is checked in jQuery?

This worked for me:

$get("isAgeSelected ").checked == true

Where isAgeSelected is the id of the control.

Also, @karim79's answer works fine. I am not sure what I missed at the time I tested it.

Note, this is answer uses Microsoft Ajax, not jQuery

Dynamically check if the checkbox is checked on-fly

You can use the querySelectorAll function to get list of checked checkbox in specific div.

If size of list > 0, it contains checked checkbox.

Check if one item or more item is checked under Doctor.
document.querySelectorAll('#doctor input[type=checkbox]:checked').length > 0
Check if one item or more item is checked under patient.
document.querySelectorAll('#patient input[type=checkbox]:checked').length > 0

adding style to li elements if checkbox is checked

Though DCR's solution is good, it doesn't work if the input gets unchecked. Here's a little modification that i've made, hope it will solve the problem!

function changeOnChecked(){
 const a = event.target.closest('input').checked;
 if(a)
  event.target.closest('li').style.color='red'
 else
   event.target.closest('li').style.color='black'
}

<ul id = "to-do-list" >
            <li> <input type="checkbox" onclick="changeOnChecked()"> to school</li>
            <li> <input type="checkbox" onclick="changeOnChecked()"> do website</li>
        </ul>

If checkbox is checked condition Javascript

I'm not sure what was going on but when I had if(checkbox == true) I was getting the message saying true is not defined as if it was looking for a variable called true.

I changed it to using Jquery like so if($("#checkbox").is(':checked'))

How can i check and unchecked detect in checkboxes inside td using jquery or javascript DOM?

To get checkbox inside clicked td you need to write $(this).find("input:checkbox").

Also to get whether checkbox is checked you need to use .is(':checked').

Try it below.

$('td').click(function() {
  var isChecked = $(this).find("input:checkbox").is(':checked');
  if (isChecked) {
    console.log('checked');
  } else {
    console.log('false');
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0/jquery.min.js"></script>
<table id="tableModul" class="w-30 table table-lg table-hover table-bordered table-striped">
  <thead class="thead-dark">
    <tr>
      <th>Department</th>
      <th>Kode Unit</th>
      <th style="width: 30px;">position_name</th>
    </tr>
  </thead>
  <tbody id="myTable">

    <tr>
      <td class="nik">DEPARTEMEN</td>
      <td class="nr">KODE UNIT</td>
      <td>
        <div class="form-check"><input type="checkbox" class="form-check-input checksboxs" style="zoom: 1.5; width:100%;"></div>
      </td>
    </tr>

    <tr>
      <td class="nik">DEPARTEMEN</td>
      <td class="nr">KODE UNIT</td>
      <td>
        <div class="form-check"><input type="checkbox" class="form-check-input checksboxs" style="zoom: 1.5; width:100%;"></div>
      </td>
    </tr>

  </tbody>
</table>

Check if all checkboxes are checked, then add class to something

You need to get the total number of checkboxes and increment a counter if a particular checkbox is ticked. If the numbers match, all checkboxes must be ticked.

function showMe (box) {
    var checkbox = document.getElementsByName("selectPlant");
    var counter=0;
    for(var i=0;i<checkbox.length;i++) {
        if(checkbox[i].checked){
            counter++;
        }
        if(counter==checkbox.length)
        {
            document.getElementById(box).classList.add('show');
        }
    }
}