I like to make the first tab open by default for tabs with css and javascript-CodePudding

Please help me to make the first tab open by default. Currently, all tabs are closed. I like to make the first tab open by default. I added a class "active" and the tab color is showing active color but the content tab is not open & showing. Any help will be appreciated!

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";
}

body {font-family: Arial;}

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

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

/* Change background color of buttons on hover */
.tab button:hover {
  background-color: #ddd;
}

/* Create an active/current tablink class */
.tab button.active {
  background-color: #ccc;
}

/* Style the tab content */
.tabcontent {
  display: none;
  padding: 6px 12px;
  border: 1px solid #ccc;
  border-top: none;
}

<div >
  <button  onclick="openCity(event, 'London')">London</button>
  <button  onclick="openCity(event, 'Paris')">Paris</button>
  <button  onclick="openCity(event, 'Tokyo')">Tokyo</button>
</div>

<div id="London" >
  <h3>London</h3>
  <p>London is the capital city of England.</p>
</div>

<div id="Paris" >
  <h3>Paris</h3>
  <p>Paris is the capital of France.</p> 
</div>

<div id="Tokyo" >
  <h3>Tokyo</h3>
  <p>Tokyo is the capital of Japan.</p>
</div>

Thank you in advance!

CodePudding user response：

The simplest thing is to call the function that opens the first tab after loading the page.

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";
  if(evt) evt.currentTarget.className  = " active";
    else document.querySelector('button.tablinks').className  = " active";
}
document.body.addEventListener('DOMContentLoaded', openCity(event, 'London'));

body {font-family: Arial;}

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

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

/* Change background color of buttons on hover */
.tab button:hover {
  background-color: #ddd;
}

/* Create an active/current tablink class */
.tab button.active {
  background-color: #ccc;
}

/* Style the tab content */
.tabcontent {
  display: none;
  padding: 6px 12px;
  border: 1px solid #ccc;
  border-top: none;
}

<div >
  <button  onclick="openCity(event, 'London')">London</button>
  <button  onclick="openCity(event, 'Paris')">Paris</button>
  <button  onclick="openCity(event, 'Tokyo')">Tokyo</button>
</div>

<div id="London" >
  <h3>London</h3>
  <p>London is the capital city of England.</p>
</div>

<div id="Paris" >
  <h3>Paris</h3>
  <p>Paris is the capital of France.</p> 
</div>

<div id="Tokyo" >
  <h3>Tokyo</h3>
  <p>Tokyo is the capital of Japan.</p>
</div>

CodePudding user response：

Just add class active to the London tab.

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";
}

body {font-family: Arial;}

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

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

/* Change background color of buttons on hover */
.tab button:hover {
  background-color: #ddd;
}

/* Create an active/current tablink class */
.tab button.active {
  background-color: #ccc;
}

/* Style the tab content */
.tabcontent {
  display: none;
  padding: 6px 12px;
  border: 1px solid #ccc;
  border-top: none;
}
.tabcontent.active{/* add this */
  display:block;
}

<div >
  <button  onclick="openCity(event, 'London')">London</button>
  <button  onclick="openCity(event, 'Paris')">Paris</button>
  <button  onclick="openCity(event, 'Tokyo')">Tokyo</button>
</div>

<div id="London" >
  <h3>London</h3>
  <p>London is the capital city of England.</p>
</div>

<div id="Paris" >
  <h3>Paris</h3>
  <p>Paris is the capital of France.</p> 
</div>

<div id="Tokyo" >
  <h3>Tokyo</h3>
  <p>Tokyo is the capital of Japan.</p>
</div>

CodePudding user response：

You just need to add the selected class in the html for the first tab and remove display:none from corresponding details pane