javascript - 如何自动显示此菜单的第一个结果？

Question

我的这个菜单有问题，当我进入我的网站时，如果我点击菜单，它只显示菜单“电影”中的内容，当我进入该网站时，它什么也没有显示，我想要相反的那，他会显示“电影”菜单的内容而无需单击它，我做错了什么？

function openCity(evt, cityName) {
  var i, tabcontent, tablinks;
  tabcontent = document.getElementsByClassName("tabcontent");
  for (i = 0; i < tabcontent.length; i++) {
    tabcontent[i].style.display = "none";
  }
  tablinks = document.getElementsByClassName("tablinks");
  for (i = 0; i < tablinks.length; i++) {
    tablinks[i].className = tablinks[i].className.replace(" active", "");
  }
  document.getElementById(cityName).style.display = "block";
  evt.currentTarget.className += " active";
}

.tab {
  overflow: hidden;
  border: 1px solid #ccc;
  background-color: #f1f1f1;
}

.tab button {
  background-color: inherit;
  float: left;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 14px 16px;
  transition: 0.3s;
  font-size: 17px;
}

.tab button:hover {
  background-color: #ddd;
}

.tab button.active {
  background-color: #ccc;
}

.tabcontent {
  display: none;
  padding: 6px 12px;
  border: 1px solid #ccc;
  border-top: none;
}

<div class="tab">
  <button class="tablinks" onclick="openCity(event, 'Filmes')">Filmes</button>
  <button class="tablinks" onclick="openCity(event, 'Series')">Séries</button>
  <button class="tablinks" onclick="openCity(event, 'Animes')">Animes</button>
  <button class="tablinks" onclick="openCity(event, 'Desenhos')">Desenhos</button>
</div>

<div id="Filmes" class="tabcontent">
  <h3>Filmes</h3>
  <p>Todos os filmes</p>
</div>

<div id="Series" class="tabcontent">
  <h3>Séries</h3>
  <p>Todas as séries</p>
</div>

<div id="Animes" class="tabcontent">
  <h3>Animes</h3>
  <p>Todos os animes</p>
</div>

<div id="Desenhos" class="tabcontent">
  <h3>Desenhos</h3>
  <p>Todos os desenhos</p>
</div>

Answer 1

我相信这可能就是您要找的。基本上，我更改了 Filmes 按钮的初始类以包含 active 并另外确保 Filmes 部分包含一个 display: block 的风格。

function openCity(evt, cityName) {
  var i, tabcontent, tablinks;
  tabcontent = document.getElementsByClassName("tabcontent");
  for (i = 0; i < tabcontent.length; i++) {
    tabcontent[i].style.display = "none";
  }
  tablinks = document.getElementsByClassName("tablinks");
  for (i = 0; i < tablinks.length; i++) {
    tablinks[i].className = tablinks[i].className.replace(" active", "");
  }
  document.getElementById(cityName).style.display = "block";
  evt.currentTarget.className += " active";
}

.tab {
  overflow: hidden;
  border: 1px solid #ccc;
  background-color: #f1f1f1;
}

.tab button {
  background-color: inherit;
  float: left;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 14px 16px;
  transition: 0.3s;
  font-size: 17px;
}

.tab button:hover {
  background-color: #ddd;
}

.tab button.active {
  background-color: #ccc;
}

.tabcontent {
  display: none;
  padding: 6px 12px;
  border: 1px solid #ccc;
  border-top: none;
}

<div class="tab">
  <button class="tablinks active" onclick="openCity(event, 'Filmes')">Filmes</button>
  <button class="tablinks" onclick="openCity(event, 'Series')">Séries</button>
  <button class="tablinks" onclick="openCity(event, 'Animes')">Animes</button>
  <button class="tablinks" onclick="openCity(event, 'Desenhos')">Desenhos</button>
</div>

<div style="display: block" id="Filmes" class="tabcontent">
  <h3>Filmes</h3>
  <p>Todos os filmes</p>
</div>

<div id="Series" class="tabcontent">
  <h3>Séries</h3>
  <p>Todas as séries</p>
</div>

<div id="Animes" class="tabcontent">
  <h3>Animes</h3>
  <p>Todos os animes</p>
</div>

<div id="Desenhos" class="tabcontent">
  <h3>Desenhos</h3>
  <p>Todos os desenhos</p>
</div>