JSFiddle - React, Tailwind, and code Playground

HTML

<select class="element">
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
</select>

<button><<<</button>

<select class="newSel">
    <option value="11">NewOne</option>
    <option value="22">NewTwo</option>
    <option value="33">NewThree</option>
</select>

JavaScript

$("button").click(function(){
    var oldSel = $('.element').get(0);

    while (oldSel.options.length > 0) {
        oldSel.remove(oldSel.options.length - 1);
    }

    var newSel = $('.newSel').get(0);
    
    for (i = 0; i < newSel.length; i++)
    {
        var opt = document.createElement('option');
        
        opt.text = newSel.options[i].text;
        opt.value = newSel.options[i].value;
        
        oldSel.add(opt, null);
    }
})