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I have here 2 viewbag in my controller

               ViewBag.MyCategory = new SelectList(db.RecyclableType, "id", "type");
               ViewBag.iddd = new SelectList(db.RecyclableType, "id", "type");

and a View

              @Html.DropDownList("iddd", (IEnumerable<SelectListItem>)ViewBag.iddd, "SELECT ITEM TYPE", new { @class = "form-control" })
              @Html.DropDownList("MyCategory", (IEnumerable<SelectListItem>)ViewBag.MyCategory, "SELECT ITEM TYPE", new { @class = "form-control"})

i tried to create a function like below but nothing is working

              document.getElementById("iddd") = document.getElementById("MyCategory");

CodePudding user response：

You can do it using jQuery

1. First on change of iddd dropdown get its value
2. Set the value to MyCategory dropdown and set the attribute to selected

$("#iddd").change(function () {
    var value = $("#iddd").val();
    $("#MyCategory").val(value).attr("selected", "selected");
});

Note: Add jQuery script file in head section

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>