JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Round to 4 Decimal Places</title>
    <script type="text/javascript" src="http://ajax.microsoft.com/ajax/jQuery/jquery-1.4.2.min.js"></script>
</head>
<body>
    <p>Type a decimal number in the TextBox, limited to 4 decimals</p>
    <input id="input" type="text" />
</body>
</html>

JavaScript

$(function() {
            $('#input').keypress(function(){
                try {
                    val = $(this).val().split('.');
                    if(val[1] > 999) return false;
                }catch(e){}
            })
        });