how to convert date format 12/12/2019 to 12-12-2019

i am using this blow code for laravel i want to date format , 12/12/2019 To 12-12-2019

code

<script>
function DDMMYYYY(value, event) {
  let newValue = value.replace(/[^0-9]/g, '').replace(/(\..*)\./g, '$1');

  const dayOrMonth = (index) => index % 2 === 1 && index < 4;

  // on delete key.  
  if (!event.data) {
    return value;
  }

  return newValue.split('').map((v, i) => dayOrMonth(i) ? v + '/' : v).join('');;
}
</script>

input

       <div class="col-md-4">
                                                   <input  type="tel" maxlength="10" placeholder="DD/MM/YYYY"
oninput="this.value = DDMMYYYY(this.value, event)" required class="form-control  " name="certificate_issue_date" id="certificate_issue_date">
                                    </div>

via Chebli Mohamed