<!-- Material unchecked -->

<div class="form-check">

  <input type="checkbox" class="form-check-input" id="x">

  <label class="form-check-label" for="x">Material unchecked</label>

</div>

<!-- Material indeterminate -->

<div class="form-check">

  <input type="checkbox" class="form-check-input" id="y" checked>

  <label class="form-check-label" for="y">Material indeterminate</label>

</div>

​

$('#y').prop('indeterminate', true);