JS
(quick guide & example)
<form id="demo" onsubmit="return send()"> <input type="text" name="name" required> <input type="email" name="email" required> <input type="submit" value="Go!"> </form>
function send () { GET FORM DATA var data = new FormData(document. getElementById("demo")); data.append("KEY", "VALUE");
INIT FETCH POST fetch("URL", { method: "POST", body: data })
SERVER RESPONSE .then(res => res.text()) .then(res => alert(txt)); return false; }