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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

HTML

            
              <h1>Indeterminate Checkboxes</h1>

<ul>
  <li>
    <input type="checkbox" name="tall" id="tall">
    <label for="tall">Tall Things</label>

    <ul>
      <li>
        <input type="checkbox" name="tall-1" id="tall-1">
        <label for="tall-1">Buildings</label>
      </li>
      <li>
        <input type="checkbox" name="tall-2" id="tall-2">
        <label for="tall-2">Giants</label>

        <ul>
          <li>
            <input type="checkbox" name="tall-2-1" id="tall-2-1">
            <label for="tall-2-1">Andre</label>
          </li>
          <li>
            <input type="checkbox" name="tall-2-2" id="tall-2-2">
            <label for="tall-2-2">Paul Bunyan</label>
          </li>
        </ul>
      </li>
      <li>
        <input type="checkbox" name="tall-3" id="tall-3">
        <label for="tall-3">Two sandwiches</label>
      </li>
    </ul>
  </li>
  <li>
    <input type="checkbox" name="short" id="short">
    <label for="short">Short Things</label>

    <ul>
      <li>
        <input type="checkbox" name="short-1" id="short-1">
        <label for="short-1">Smurfs</label>
      </li>
      <li>
        <input type="checkbox" name="short-2" id="short-2">
        <label for="short-2">Mushrooms</label>
      </li>
      <li>
        <input type="checkbox" name="short-3" id="short-3">
        <label for="short-3">One Sandwich</label>
      </li>
    </ul>
  </li>
</ul>

<p>This version is a fork of <a href="https://codepen.io/chriscoyier/pen/JYyXjX">https://codepen.io/chriscoyier/pen/JYyXjX</a> posted on twitter at <a href="https://twitter.com/chriscoyier/status/1167014134191468546">https://twitter.com/chriscoyier/status/1167014134191468546</a></p>
            
          
!

CSS

            
              body {
  padding: 20px;
}
ul { 
  list-style: none;
  margin: 5px 20px;
}
li {
  margin: 10px 0;
}
            
          
!

JS

            
              var inputSelector = 'input[type="checkbox"]';
var listSelector = 'ul';
// select the root of the complete list
var mainListElement = document.querySelector(listSelector);
// select ALL checkboxes that are in the list
let checkboxes = mainListElement.querySelectorAll(
  'ul input[type="checkbox"]'
);

// apply the event listener to all items
checkboxes.forEach((element) => {
  element.addEventListener('click', () => {
    switchChilds.call(element);
    if (this.checked) {
      this.indeterminate = false;
    }
    indeterminateParents.call(element, mainListElement);
  });
});

// selects all child input checkboxes and applies the checked
// item of the one that has been clicked on
function switchChilds() {
  let childs = this.parentElement.querySelectorAll(listSelector + ' ' + inputSelector);
  childs.forEach((element) => {
    element.checked = this.checked;
  });
}

// checks if the childs is somewhere in the DOM of the parent
function contains(parent, child) {
  /*
  found at:
  https://stackoverflow.com/questions/2234979/how-to-check-in-javascript-if-one-element-is-contained-within-another
  */
  var node = child.parentNode;
     while (node != null) {
         if (node == parent) {
             return true;
         }
         node = node.parentNode;
     }
     return false;
}

// checks if all given checkboxes are unchecked
function allUnchecked(checkboxes) {
  var isChecked = false;
  checkboxes.forEach((item, index) => {
    if (item.checked) {
      isChecked = true;
    }
  });
  return !isChecked;
}

// updates the indeterminate status of the parents
function indeterminateParents(ul) {
  let childs = ul.childNodes;
  for (i = 0; i < childs.length; ++i) {
    if (contains(childs[i], this) === false) {
      continue;
    }
    let nextCheckbox = childs[i].querySelector(inputSelector);
    if (nextCheckbox === this) {
      return true;
    }
    let allDescendantBoxes = childs[i].querySelectorAll(inputSelector);
    if (allUnchecked(allDescendantBoxes)) {
      nextCheckbox.indeterminate = false;
    } else {
      nextCheckbox.indeterminate = true;
    }
    indeterminateParents.call(this, childs[i].querySelector(listSelector));
    break;
  }
  return true;
}

            
          
!
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