How to remove and replace select options using jquery?

Question

Need a little help here. I have a dynamic form that enables user to select his/her correct addresses. What I did is I have 2 select boxes. One is States and second is city. After the user choose his/her states the dropdown city options will be change dynamically according to the selected states. My problem is, I am appending it. That's why I have a problem changing the correct city. Because it will display the previous selected option value. It keeps on appending and appending. Any idea how can I work on this? Here's my code.

$('#state').on('change',function(){    
    var state_code = $('#state').val();    
    var city_url = '<?php echo site_url("locations/displayCity/' + state_code + '"); ?>';    
    $.ajax({    
        type: 'POST',
        url: city_url,
        data: '',
        dataType: 'json',
        async: false,
        success: function(i){    
            var select = $('#city');    
            for (var j = 0; j < i.length; j++){                 
                console.log(i[j].name + "--" + i[j].id);
                $("#city").append("<option value='" +i[j].name+ "'>" +i[j].name+ "</option>");    
            }    
        }    
    });    
});

Here's the select for city:

<select id="city" name="city">
    <option value="">---Select City---</option>
</select>

Answer 1

Removes all options and appends your default one again:

var select = $('#city'); select.empty().append('<option value="">---Select City---</option>'); 

http://api.jquery.com/empty/

Answer 2

You can do the following:

var selectbox = $('#city');
selectbox.empty();
var list = '';
for (var j = 0; j < i.length; j++){
        list += "<option value='" +i[j].name+ "'>" +i[j].name+ "</option>";
}
selectbox.html(list);

Note: Don't call the append method in the loop and also cache the selectors.

Answer 3

this is the native java-script correct working form:

// get the select html element by id
var selectElement = document.getElementById('city');

// remove all options from select
selectElement.options.length = 0;

// create new option element
var newOptionElement = document.createElement('option');
newOptionElement.value = "optionValue";
newOptionElement.innerHTML = "option display text";

// add the new option into the select
selectElement.appendChild(newOptionElement);

Working Fiddle example