在弹出窗口中使用Cookie后，弹出窗口不起作用

Question

在关于Stack Overflow的几个问题让我的jQuery弹出窗口存储cookie而不再次显示之后，我在网页的其余部分上方的页面上方留了一个框，该框将网站向下推。我似乎无法弄清楚为什么它没有在页面上弹出时显示，在实现使用Cookie之前，它将覆盖在页面上并阻止用户与页面进行交互。

function setCookie(cname, cvalue) {
  window.document.cookie = cname + "=" + cvalue;
}

function getCookie(cname) {
  var ca = decodeURIComponent(document.cookie).split(';');
  for (var i = 0; i < ca.length; i++) {
    var c = ca[i].trim().split('=');
    if (cname == c[0] && c.length > 1) {
      return c[1];
    }
  }
  return "";
}

function checkCookie() {
  if (getCookie("ageverification") == "") {
    $('#popup, #overlay').show();
    $('#popup a.close').click(function(event) {
      event.preventDefault();
      $('#popup').hide();
      setCookie("ageverification", 'true');
    });
    $('#popup a.goBack').click(function(event) {
      event.preventDefault();
      goBack();
    });
  } else {
    return null;
  }
}

function goBack() {
  window.history.go(-2);
}
$(function() {
  checkCookie();
});

#overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: #000;
  filter: alpha(opacity=70);
  -moz-opacity: 0.7;
  -khtml-opacity: 0.7;
  opacity: 0.7;
  z-index: 100;
  display: none;
}

.cnt223 a {
  text-decoration: none;
}

.popup {
  width: 100%;
  margin: 0 auto;
  display: none;
  position: fixed;
  z-index: 101;
}

.cnt223 {
  min-width: 300px;
  width: 300px;
  min-height: 150px;
  margin: 100px auto;
  background: #f3f3f3;
  position: relative;
  z-index: 103;
  padding: 15px 35px;
  border-radius: 5px;
  box-shadow: 0 2px 5px #000;
}

.cnt223 p {
  clear: both;
  color: #555555;
  /* text-align: justify; */
  font-size: 20px;
  font-family: sans-serif;
}

.cnt223 p a {
  color: #d91900;
  font-weight: bold;
}

.cnt223 .x {
  float: right;
  height: 35px;
  left: 22px;
  position: relative;
  top: -25px;
  width: 34px;
}

.cnt223 .x:hover {
  cursor: pointer;
}

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id='popup' style="display:none">
  <div class='cnt223'>
    <h1>Important Notice</h1>
    <p>
      You must be over 18 to purchase products containing nicotene, or nicotene related products!
      <br />
      <br />
      <a href='' class='close' style="color:green">I am 18+</a>
      <a href='' class='goBack' style="color:red">I am under 18</a>
    </p>
  </div>
</div>
<script>
</script>

Answer 1

您只想显示一次消息。

您需要使用javascript sessionStorage函数来完成此操作。

  

localStorage和sessionStorage属性允许保存键/值   在网络浏览器中配对。

     

sessionStorage对象仅存储一个会话的数据（数据   在关闭浏览器标签时被删除）。

这里是示例：

$(function () {
    if (!sessionStorage.getItem('firstVisit') == "1") {
        $("#popup").show();
        sessionStorage.setItem('firstVisit', '1');
    }

    $('#popup a.close').click(function (event) {
        $('#popup').hide();
    });
});

function goBack() {
    window.history.go(-2);
}
           

#overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: #000;
  filter: alpha(opacity=70);
  -moz-opacity: 0.7;
  -khtml-opacity: 0.7;
  opacity: 0.7;
  z-index: 100;
  display: none;
}

.cnt223 a {
  text-decoration: none;
}

.popup {
  width: 100%;
  margin: 0 auto;
  display: none;
  position: fixed;
  z-index: 101;
}

.cnt223 {
  min-width: 300px;
  width: 300px;
  min-height: 150px;
  margin: 100px auto;
  background: #f3f3f3;
  position: relative;
  z-index: 103;
  padding: 15px 35px;
  border-radius: 5px;
  box-shadow: 0 2px 5px #000;
}

.cnt223 p {
  clear: both;
  color: #555555;
  /* text-align: justify; */
  font-size: 20px;
  font-family: sans-serif;
}

.cnt223 p a {
  color: #d91900;
  font-weight: bold;
}

.cnt223 .x {
  float: right;
  height: 35px;
  left: 22px;
  position: relative;
  top: -25px;
  width: 34px;
}

.cnt223 .x:hover {
  cursor: pointer;
}

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id='popup' style="display:none">
  <div class='cnt223'>
    <h1>Important Notice</h1>
    <p>
      You must be over 18 to purchase products containing nicotene, or nicotene related products!
      <br />
      <br />
      <a href='' class='close' style="color:green">I am 18+</a>
      <a href='' class='goBack' style="color:red">I am under 18</a>
    </p>
  </div>
</div>