index.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>Push js</title>
    <script src="push.js"></script>
</head>
<body>

    <button onclick="notify()">Notify !</button>
    <button onclick="check()">Check !</button>
    
    <script>
        function notify(){
            Push.create("Hello world !", {
                body: "This is body !",
                icon: '/icon.png',
                timeout: 4000,
                onClick: () => {
                    window.focus()
                    this.close()
                }
            })
        }

        function check(){
            console.log(Push.Permission.has())
        }
    </script>
</body>
</html>