JSFiddle - React, Tailwind, and code Playground

HTML

<form name="input" method="post" action="#">
Display Tag:<input type="text" name="taginput">
<input type="submit" value="Go">
<select name="tags" multiple>
    <option value="C#">C#</option>
    <option value="Java">Java</option>
    <option value="Javascript">Javascript</option>
    <option value="PHP">PHP</option>
    <option value="Android">Android</option>
    <option value="jQuery">jQuery</option>
    <option value="C++">C++</option>
    <option value="Python">Python</option>
    <option value="HTML">HTML</option>
    <option value="MySQL">MySQL</option>
    </select>
</form>

JavaScript

$("select[name=tags]").change(function() {
    var arrSelected = $(this).find("option:selected").map(function() {
        return $(this).text();
    }).get();
    
    $("input[name=taginput]").val(arrSelected);
});