Push values from cookie to a multiple select in javascript

Question

I have created a multiple select object in my html and I want to set up the cookies so that whenever I reload the website, I get the selected values from the last session.

In order to set up the cookies, I have used the following javascript code:

window.onload = function(){
    if(document.cookie.length != 0){
        var nameValuearray = document.cookie.split("=");
        list_values_selected=nameValuearray[1].split(",");
        document.getElementById("ms_example2_sinB").value= list_values_selected;
    }
}

function  getvaluecookie(){
var d = new Date();
    <!--Se define el tiempo en el que expirará la cookie-->
    d.setTime(d.getTime() + (360*24*3600*1000));
    var expires = "expires="+d.toUTCString();
    <!--Se obtiene la lista de valores seleccionados-->
    var selectedflavor = $("#ms_example2_sinB").val();

    if (selectedflavor!="None selected"){
        document.cookie= "flavor=" + selectedflavor + ";" + expires;
    }
}  

However, this doesn´t work as I want it to work. The cookie is correctly generated but I cannot manage to push the values from the list list_values_selected as selected values in the dropdown.

The html code is:

<form  name="prueba_sin_B" method="POST" action="/" onsubmit="getvaluecookie()">
            <select multiple  id="ms_example2_sinB" name="select" >
                    <option value="Cheese" >Cheese</option>
                    <option value="tomatoes" >Tomatoes</option>
                    <option value="mozarella" >Mozzarella</option>
                    <option value="mushrooms" >Mushrooms</option>
                    <option value="pepperoni" >Pepperoni</option>
                    <option value="onions" >Onions</option>
                </select>
            </div>
            <input type="submit" value="Submit" >
        </div>
    </form>

Thank you!

Answer 1

To make the options selected in multiselect, you have to set each option's selected property to true
Use below code for window.onload

window.onload = function(){
    if(document.cookie.length != 0){
        var nameValuearray = document.cookie.split("=");
        list_values_selected=nameValuearray[1].split(",");
        $.each(list_values_selected, function(i,e){
            $("#ms_example2_sinB option[value='" + e + "']").prop("selected", true);
        });
    }
}