<select class="select">

  <option value="1">One</option>

  <option value="2">Two</option>

  <option value="3">Three</option>

  <option value="4" selected>Four</option>

  <option value="5">Five</option>

  <option value="6">Six</option>

  <option value="7">Seven</option>

  <option value="8">Eight</option>

</select>

​

<button class='btn btn-primary btn2'>

  setValue('2')

</button>

<button class='btn btn-primary btn6'>

  setValue('6')

</button>

​

const selectEl = document.querySelector('.select')

const selectInstance = mdb.Select.getInstance(selectEl)

const btn2 = document.querySelector('.btn2')

const btn6 = document.querySelector('.btn6')

​

// Get the selected option element and value

const selectedOption = document.querySelector('.select option[selected]');

​

if(selectedOption) {

  // set default value using MDB Select method instead of 'selected' attr

  selectInstance.setValue(selectedOption.value)

  // Remove the 'selected' attribute

  selectedOption.removeAttribute('selected');

}

​

​

btn2.addEventListener('click', () => selectInstance.setValue('2'))

btn6.addEventListener('click', () => selectInstance.setValue('6'))

​