JSFiddle - React, Tailwind, and code Playground

by ampersand

HTML

<input type="text" id="amount" size="30" />
<span id="span_combo">
     <select name="foo" id="combo">
           <option value="1">1</option>  
           <option value="2">2</option>
     </select>
</span>

JavaScript

$("#amount").keyup(function(){
        var flag;
        $("#combo").show("slow");
        var a = $("#amount").val();
        if(a==""){
            $("#span_combo option").remove();
        }
        a=parseInt(a);
        for(var i=1;i<=a-1;i++){
                $("#combo").append('<option value="'+i+'">'+i+'</option>');
        }
    });