Multiple option in select tag is not working in new window

Question

I want to select multiple items for this i added multiple but it is not working. Here is my code

<select class="form-control" name="columnValues[]" id="selectbox" multiple="multiple" size="5">
    <option value="">Select</option>
    <option value="I1">I1</option>
    <option value="I2">I2</option>
    <option value="I3">I3</option>
    <option value="I4">I4</option>
    <option value="I5">I5</option>
    <option value="I6">I6</option>
    <option value="I7">I7</option>
</select>

Answer 1

Just try below code and hold down the Ctrl (windows) / Cmd (Mac) button to select multiple options. -

<select class="form-control" name="columnValues[]" id="selectbox" multiple> 
  <option value="">Select</option> 
  <option value="I1">I1</option> 
  <option value="I2">I2</option> 
  <option value="I3">I3</option> 
  <option value="I4">I4</option> 
  <option value="I5">I5</option> 
  <option value="I6">I6</option> 
  <option value="I7">I7</option>
</select>