JavaScript: Auto-Tick Checkbox (Real-Time)

by MythOfEchelon

HTML

<!DOCTYPE html> <!-- This is just my basic HTML5 template. Make sure you set this up correctly for your personal needs -->

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title></title>
        
        <style type="text/css">
            * {
                margin: 0;
                padding: 0;
            }
            
            div {
                float: left;
            }
            
            #wrapper {
                width: 200px;
            }
        </style>
    </head>
    
    <body>
        <div id="wrapper">
            <div id="numberPlate_Wrapper">
                <span>Number Plate: </span>
                <input type="text" id="numberPlate" onInput="textBox()" />
            </div>
            <div id="noNumberPlate_Wrapper">
                <span>No Number Plate: </span>
                <input type="checkbox" id="noNumberPlate" onClick="checkBox()" />
            </div>
        </div>
        
        <script type="text/javascript">
            window.onload = initAll();
            function initAll(){
                numberPlate = document.getElementById("numberPlate");
                noNumberPlate = document.getElementById("noNumberPlate");
                
                textBox();
                checkBox();
            }
            
            function textBox(){
                if ((!numberPlate.value)){
                    noNumberPlate.checked = true;
                } else {
                    noNumberPlate.checked = false;
                }
            }
            
            function checkBox(){
                if ((numberPlate.value) && (noNumberPlate.checked == false)){
                    numberPlate.value = "";
                }
            }
        </script>
    </body>
</html>