jQuery 点击后退（返回）执行函数

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<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>点击后退</title>
    <script type="text/javascript" src="http://code.jquery.com/jquery-3.3.1.js"></script>
    <script>
        jQuery(document).ready(function ($) {
            if (window.history && window.history.pushState) {
                $(window).on('popstate', function () {
                    var hashLocation = location.hash;
                    var hashSplit = hashLocation.split("#!/");
                    var hashName = hashSplit[];
                    if (hashName !== '') {
                        var hash = window.location.hash;
                        if (hash === '') {
                            alert("希望该网站能提供你帮助！");
                        }
                    }
                });
                window.history.pushState('forward', null, './#forward');
            }
        });
    </script>
</head>
<body>
<h3>阅谁问君诵，水落清香浮。</h3>

</body>
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