JSFiddle - React, Tailwind, and code Playground

HTML

<div id="formdiv">
    <form name="form1" id="form1" class="js-php">
        Mata in ett nummer: 
        <input id="fill1" name="fill1" type="text" />
        <input type="submit" id="submit1" name="submit1" value="submit">
    </form>
</div>

JavaScript

$(".js-php").submit(function(e){
    data = $(this).serialize(); 
    $.ajax({
        type:"GET",
        datatype:"json",
        url:"/echo/json/",
        data: data,
        success: function (data){
            $("#formdiv").append("Your input: "+data)
            alert (data);
        }
    })
    return false;
});