JSFiddle - React, Tailwind, and code Playground

HTML

<div id="selectContainer">
    <p><select class="my-select"></select></p>
</div>

<p><button id="addOneMore">+ Ekle</button></p>

JavaScript

var elements = ["Asuman", "Ahmet", "Ali", "Ayşe", "Mehmet"];
var selectedElements = [];

/**
 * Adds an option to a select object
 */
function addOption(select, optVal, opt) {
    var opt = $("<option />").attr('value', optVal).text(opt);
    select.append(opt);
}

/**
 * Adds all available options to a select object
 */
function addOptions(select) {
    for (var i = 0; i < elements.length; i++) {
        var element = elements[i];
        addOption(select, element, element);
    }
    
    // remove new selected element from available elements
    var e = elements.splice(0, 1)[0];
    // add it to selectedElements array
    selectedElements.push(e);
    
    removeOptions(e, select);
}

/**
 * Removes an option from a given select object
 */
function removeOption(select, optionValue) {
    var option = select.find('option[value="' + optionValue + '"]');
    option.remove();
}

/**
 * Removes an option from all select objects except the given
 */
function removeOptions(optionValue, excludeSelect) {
    var selects = $(".my-select").not(excludeSelect);
    for (var i = 0; i < selects.length; i++) {
        var select = $(selects[i]);
        removeOption(select, optionValue);
    }
}

/**
 * Adds a new select element when the add button is pressed.
 */
function addSelect() {
    if (elements.length == 0) {
        return;
    }
    var select = $("<select />").addClass("my-select");
    var p = $("<p />").append(select);
    addOptions(select);
    $("#selectContainer").append(p);
}

/**
 * Adds a value to and remove a value from all selects except the given select
 */
function replaceOptions(addValue, removeValue, excludeSelect) {
    var selects = $(".my-select").not(excludeSelect);
    for (var i = 0; i < selects.length; i++) {
        var select = $(selects[i]);
        removeOption(select, removeValue);
        addOption(select, addValue, addValue);
    }
}

/**
 * Called when a selection changes
 */
function selectionChange() {
    var select = $(this);
   ...