test-7.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Test number seven</title>
    <style>
        #rectangle{
            width: 50px;
            height: 20px;
            background: green;
            margin-bottom: 20px;
            visibility: hidden;
        }
    </style>
</head>
<body>
    <div id="rectangle"></div>
    <form name="" onclick="fun()">
        <input type="text" name="" oninput="fun2()">
    </form>
    <script>
        function fun(){
            document.getElementById('rectangle').style.visibility = 'visible'
        }
        function fun2(){
            document.getElementById('rectangle').style.visibility = 'hidden';
        }
        function fun3(){
            document.getElementById('rectangle').style.visibility = 'hidden';
        }
    </script>
</body>
</html>