I have a problem when trying to set selected option from javascript. I created one select and added options with php from mysql like this:

<select class="form-control input-group-lg" name="progress" id="progress">
<?php
  if ($conn === false) {
    die("ERROR: Could not connect. " . mysqli_connect_error());
  }

  $sql = "SELECT * FROM progress";
  if ($result = mysqli_query($conn, $sql)) {
    if (mysqli_num_rows($result) > 0) {
      while ($row = mysqli_fetch_array($result)) {
        $id = $row['id'];
        $progress_name = $row['name'];
        echo "<option>$progress_name</option>";
      }
    }
    else {
      echo "<option>Fault!</option>";
    }
  }
  else {
    echo "$sql. " . mysqli_error($conn);
  }
  mysqli_close($conn);
?>
</select>

And then set selected option from javascript like this:

$('#progress').val("Value to set");

This method works fine and it sets selected option with that value which I want.

ANOTHER METHOD:

I have php file and I select data from database (MySQL) in json and then using ajax like this

$.ajax({
  url: 'data_control/orders/progress_select.php',
  type: 'get',
  method: "POST",
  data: {selected_value:selected_value},
  dataType: 'JSON',
  success: function (response) {
    var len = response.length;
    for (var i = 0; i < len; i++) {
      var progress_name = response[i].progress_name;
      var option = document.createElement("option");
      option.text = progress_name;
      option.value = progress_name;
      var select = document.getElementById('progress');
      select.appendChild(option);
    }
  }
});

Options are added successfully, but I can't set selected value in this way:

$('#progress').val("Value to set");

Thanks for help!