JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div id="chat-box">
        <input type="text" name="numberEntry" id="number">

    </div>
    <script src="jquery-2.2.1.js"></script>
    <script src="game.js"></script>
</body>

CSS

body{
    background-color:#51a858;
}

#chat-box{
    background-color:#ffffff;
    width:550px;
    height:450px;
    margin:0 auto;
    position:relative;
    top:130px;
    overflow: scroll;
}

input#number{
    width:320px;
    height:20px;
    margin: 0 auto;
    position: relative;
    left:20%;
    top:10px;
    border:1px solid #000;

}

.human{
    background-color:#0026ff;
    color:white;
    text-align:right;
    margin-left: 70%;
    margin-right: 30px;
}

.comp{
    background-color:#a70a90;
    color:#fecdcd;
    position:relative;
    left:10px;
    text-align:left;
    margin-right:60%;
}

.guess{
   text-align:center;
}

JavaScript

/*

Program/Project: Guessing Game with isNan()

Name: Ben Fuller

Date: 2/2/2016

Description: Lets a user guess a number. If user guesses a letter, they need to try again. Otherwise, it is the same guessing game as before.

Instructor: Matt Banz 

Section: 01

*/
$(document).ready(function () {
    $("#chat-box").append('<div class="guess"><br>Guess a number between 1-100</div>');
});
var number = Math.round((Math.random() * 100)) % 100 + 1;

document.getElementById('number').addEventListener('keydown', function (event) {


    if (event.which === 13 || event.keyCode === 13) {
        var guess = this.value;       

            if (guess == number) {               
                $("#chat-box").append('<div class="human">' + guess + '</div>');
                $("#chat-box").append('<div class="comp">You guessed it!</div>');
            } else if (isNaN(guess)) {
                $("#chat-box").append('<div class="human">' + guess + '</div>')
                $("#chat-box").append('<div class="comp">' + guess + ' is not a valid guess. Try again.</div>');
            } else if (guess == 0) {
                $("#chat-box").append('<div class="human">' + guess + '</div>')
                $("#chat-box").append('<div class="comp">' + guess + ' is not a valid guess. Try again.</div>');
            } else if (parseInt(guess))  {
                $("#chat-box").append('<div class="human">' + guess + '</div>')
                $("#chat-box").append('<div class="comp">' + guess + ' is not a valid guess. Try again.</div>');
            } else if (guess < number) {
                $("#chat-box").append('<div class="human">' + guess + "</div>")
                $("#chat-box").append('<div class="comp">' + guess + " is too small, guess again.</div>");
            } else if (guess > number) {
                $("#chat-box").append('<div class="human">' + guess + "</div>")
                $("#chat-box").append('<div class="comp">' + guess + " is too big, guess again.</div>");
      ...