function updateAvailability() { if (this.responseText === "y") { document.getElementById("avail").innerHTML = "Available!"; } else { document.getElementById("avail").innerHTML = "Not available"; } } function checkAvailability() { var name = document.getElementById("name").value; if (name === "") { document.getElementById("avail").innerHTML = ""; return } document.getElementById("avail").innerHTML = "Checking availability..."; var req = new XMLHttpRequest(); req.addEventListener("load", updateAvailability); req.open("GET", "/api/check_availability?name="+encodeURIComponent(name)); req.send(); }