js 常规用法（慢慢积累）是否离开当前页面

关闭页面提示

<script type="text/javascript">
    var DispClose = true;

    function CloseEvent() {
        if (DispClose) {
            return "是否离开当前页面?";
        }
    }
    window.onbeforeunload = CloseEvent;
</script>