JSFiddle - React, Tailwind, and code Playground

HTML

<select><option>---</option><option>Hello</option><option>World</option></select>

<script type="text/javascript">
    var encoded_json_from_php = '{"Hello":[1,2,3], "World":[4,5,6]}';
    var json = JSON.parse(encoded_json_from_php);
</script>

JavaScript

$(function(){
   
    $("select").change(function(){
        $(this).unbind("change");
        var val = json[$(this).val()];
        var select = $(this);
        $(this).empty();
        $.each(val, function(i,v){
            select.append("<option>"+v+"</option>");
        });
    });
    
});