Слушатель становится тупым.Вот способ защитить слушателя, добавив div и добавив новые элементы чата.
var chatinput = document.getElementById("chatinput");
var body = document.getElementById("body");
var username;
var inp = null;
var message = "";
username = prompt("Enter a username:", "Username");
if (username !== null) {
inp = username.toLowerCase();
}
while (inp === null || inp === "" || inp == "username" || inp.includes("fuck") || inp.includes("ass") || inp.includes("shit") || inp.includes("*")) {
username = prompt("That's not an appropriate username...", "Username");
if (username !== null) {
inp = username.toLowerCase();
}
}
function sendchat() {
var objchatAreaElem = document.getElementById("chatArea");
var newMessageElem = document.createElement('p');
message = "[" + username + "]: " + chatinput.value;
newMessageElem.appendChild(document.createTextNode(message));
objchatAreaElem.appendChild(newMessageElem );
chatinput.value = "";
}
addEventListener("keyup", function(event) {
if (event.keyCode == 13) {
sendchat();
}
});
* {
transition-duration: 0.5s;
scroll-behavior: smooth;
}
body {
background-color: black;
}
div {
width: 100%;
text-align: justify;
}
h1 {
font: 8vw courier;
color: white;
}
h2 {
font: 7vw courier;
color: white;
}
h3 {
font: 6vw courier;
color: white;
}
h4 {
font: 5vw courier;
color: white;
}
h5 {
font: 4vw courier;
color: white;
}
h6 {
font: 3vw courier;
color: white;
}
p {
font: 2vw courier;
color: white;
}
button, input, a {
text-decoration: none;
font: 2vw courier;
color: cyan;
border: 0.2vw solid cyan;
border-radius: 1vw;
background-color: darkblue;
}
a:hover, input:hover, button:hover {
background-color: blue;
box-shadow: 0px 0px 2.5vw white;
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>Stuff</title>
<link href="/logo.png" rel="icon">
<link href="/style.css" rel="stylesheet">
</head>
<body id="body">
<p>Message: <input id="chatinput"></p>
<div id="chatArea"></div>
<script src="script.js"></script>
</body>
</html>