Cannot read property 'addEventListener' of null while trying to make tabs work

up vote
-1
down vote

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So for some reason, it returns as Cannot read property 'addEventListener' of null in my console. Trying to make the tabs work. Can't find what is wrong with the code. Any help would be appreciated. Or if you could give me a better way of how to make tabs with JS.

This is my Javascript code

function onTabClick(event) {

  let activeTabs = document.querySelectorAll(".active");



  



  activeTabs.forEach(function(tab) {

    tab.className = tab.className.replace("active", "");

  });



  // activate new tab and panel

  event.target.parentElement.className += " active";

  document.getElementById(event.target.href.split("#")[1]).className +=

    " active";

}



var element = document.getElementById("nav-tab");

element.addEventListener("click", onTabClick, false);

And this is my HTML



<div class="container">

        <!-- Tab panes -->

        <div class="tab-content">

          <div class="tab-pane active" id="home">

            <h4>Home Panel Content</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis.

            </p>

          </div>

          <div class="tab-pane" id="profile">

            <h4>Profile Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis. Lorem ipsum dolor sit amet consectetur

              adipisicing elit. Alias distinctio, tempora incidunt aliquid

              adipisci, minus rerum optio libero quae provident sed at

              dignissimos, quia nostrum! Fuga dolorum quia hic magni.

            </p>

          </div>

          <div class="tab-pane" id="messages">

            <h4>Messages Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur, adipisicing elit. Fugiat

              quos, at qui aspernatur minus animi hic sunt necessitatibus

              incidunt molestiae reprehenderit ratione neque odit ipsa. Nemo

              laborum consequatur adipisci beatae!

            </p>

          </div>

          <div class="tab-pane" id="settings">

            <h4>Settings Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Minima

              possimus sed odit iste vitae, magnam amet illum laudantium ea!

              Fugiat consectetur consequuntur qui eos obcaecati sequi ipsam

              repellat vero voluptate.

            </p>

          </div>

        </div>

        <!-- Tabs -->

        <ul id="nav-tab" class="nav">

          <li class="active"><a href="#home">Home</a></li>

          <li><a href="#profile">Profile</a></li>

          <li><a href="#messages">Messages</a></li>

          <li><a href="#settings">Settings</a></li>

        </ul>

      </div>

asked Nov 11 at 4:00

Igor Voytt

Works perfectly fine. Press "Run code snippet".
– CertainPerformance
Nov 11 at 4:01

add a comment |

up vote
-1
down vote

favorite

This is my Javascript code

function onTabClick(event) {

  let activeTabs = document.querySelectorAll(".active");



  



  activeTabs.forEach(function(tab) {

    tab.className = tab.className.replace("active", "");

  });



  // activate new tab and panel

  event.target.parentElement.className += " active";

  document.getElementById(event.target.href.split("#")[1]).className +=

    " active";

}



var element = document.getElementById("nav-tab");

element.addEventListener("click", onTabClick, false);

And this is my HTML



<div class="container">

        <!-- Tab panes -->

        <div class="tab-content">

          <div class="tab-pane active" id="home">

            <h4>Home Panel Content</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis.

            </p>

          </div>

          <div class="tab-pane" id="profile">

            <h4>Profile Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis. Lorem ipsum dolor sit amet consectetur

              adipisicing elit. Alias distinctio, tempora incidunt aliquid

              adipisci, minus rerum optio libero quae provident sed at

              dignissimos, quia nostrum! Fuga dolorum quia hic magni.

            </p>

          </div>

          <div class="tab-pane" id="messages">

            <h4>Messages Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur, adipisicing elit. Fugiat

              quos, at qui aspernatur minus animi hic sunt necessitatibus

              incidunt molestiae reprehenderit ratione neque odit ipsa. Nemo

              laborum consequatur adipisci beatae!

            </p>

          </div>

          <div class="tab-pane" id="settings">

            <h4>Settings Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Minima

              possimus sed odit iste vitae, magnam amet illum laudantium ea!

              Fugiat consectetur consequuntur qui eos obcaecati sequi ipsam

              repellat vero voluptate.

            </p>

          </div>

        </div>

        <!-- Tabs -->

        <ul id="nav-tab" class="nav">

          <li class="active"><a href="#home">Home</a></li>

          <li><a href="#profile">Profile</a></li>

          <li><a href="#messages">Messages</a></li>

          <li><a href="#settings">Settings</a></li>

        </ul>

      </div>

asked Nov 11 at 4:00

Igor Voytt

Works perfectly fine. Press "Run code snippet".
– CertainPerformance
Nov 11 at 4:01

add a comment |

up vote
-1
down vote

favorite

This is my Javascript code

function onTabClick(event) {

  let activeTabs = document.querySelectorAll(".active");



  



  activeTabs.forEach(function(tab) {

    tab.className = tab.className.replace("active", "");

  });



  // activate new tab and panel

  event.target.parentElement.className += " active";

  document.getElementById(event.target.href.split("#")[1]).className +=

    " active";

}



var element = document.getElementById("nav-tab");

element.addEventListener("click", onTabClick, false);

And this is my HTML



<div class="container">

        <!-- Tab panes -->

        <div class="tab-content">

          <div class="tab-pane active" id="home">

            <h4>Home Panel Content</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis.

            </p>

          </div>

          <div class="tab-pane" id="profile">

            <h4>Profile Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis. Lorem ipsum dolor sit amet consectetur

              adipisicing elit. Alias distinctio, tempora incidunt aliquid

              adipisci, minus rerum optio libero quae provident sed at

              dignissimos, quia nostrum! Fuga dolorum quia hic magni.

            </p>

          </div>

          <div class="tab-pane" id="messages">

            <h4>Messages Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur, adipisicing elit. Fugiat

              quos, at qui aspernatur minus animi hic sunt necessitatibus

              incidunt molestiae reprehenderit ratione neque odit ipsa. Nemo

              laborum consequatur adipisci beatae!

            </p>

          </div>

          <div class="tab-pane" id="settings">

            <h4>Settings Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Minima

              possimus sed odit iste vitae, magnam amet illum laudantium ea!

              Fugiat consectetur consequuntur qui eos obcaecati sequi ipsam

              repellat vero voluptate.

            </p>

          </div>

        </div>

        <!-- Tabs -->

        <ul id="nav-tab" class="nav">

          <li class="active"><a href="#home">Home</a></li>

          <li><a href="#profile">Profile</a></li>

          <li><a href="#messages">Messages</a></li>

          <li><a href="#settings">Settings</a></li>

        </ul>

      </div>

asked Nov 11 at 4:00

Igor Voytt

This is my Javascript code

function onTabClick(event) {

  let activeTabs = document.querySelectorAll(".active");



  



  activeTabs.forEach(function(tab) {

    tab.className = tab.className.replace("active", "");

  });



  // activate new tab and panel

  event.target.parentElement.className += " active";

  document.getElementById(event.target.href.split("#")[1]).className +=

    " active";

}



var element = document.getElementById("nav-tab");

element.addEventListener("click", onTabClick, false);

And this is my HTML



<div class="container">

        <!-- Tab panes -->

        <div class="tab-content">

          <div class="tab-pane active" id="home">

            <h4>Home Panel Content</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis.

            </p>

          </div>

          <div class="tab-pane" id="profile">

            <h4>Profile Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis. Lorem ipsum dolor sit amet consectetur

              adipisicing elit. Alias distinctio, tempora incidunt aliquid

              adipisci, minus rerum optio libero quae provident sed at

              dignissimos, quia nostrum! Fuga dolorum quia hic magni.

            </p>

          </div>

          <div class="tab-pane" id="messages">

            <h4>Messages Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur, adipisicing elit. Fugiat

              quos, at qui aspernatur minus animi hic sunt necessitatibus

              incidunt molestiae reprehenderit ratione neque odit ipsa. Nemo

              laborum consequatur adipisci beatae!

            </p>

          </div>

          <div class="tab-pane" id="settings">

            <h4>Settings Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Minima

              possimus sed odit iste vitae, magnam amet illum laudantium ea!

              Fugiat consectetur consequuntur qui eos obcaecati sequi ipsam

              repellat vero voluptate.

            </p>

          </div>

        </div>

        <!-- Tabs -->

        <ul id="nav-tab" class="nav">

          <li class="active"><a href="#home">Home</a></li>

          <li><a href="#profile">Profile</a></li>

          <li><a href="#messages">Messages</a></li>

          <li><a href="#settings">Settings</a></li>

        </ul>

      </div>

function onTabClick(event) {

  let activeTabs = document.querySelectorAll(".active");



  



  activeTabs.forEach(function(tab) {

    tab.className = tab.className.replace("active", "");

  });



  // activate new tab and panel

  event.target.parentElement.className += " active";

  document.getElementById(event.target.href.split("#")[1]).className +=

    " active";

}



var element = document.getElementById("nav-tab");

element.addEventListener("click", onTabClick, false);

And this is my HTML



<div class="container">

        <!-- Tab panes -->

        <div class="tab-content">

          <div class="tab-pane active" id="home">

            <h4>Home Panel Content</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis.

            </p>

          </div>

          <div class="tab-pane" id="profile">

            <h4>Profile Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis. Lorem ipsum dolor sit amet consectetur

              adipisicing elit. Alias distinctio, tempora incidunt aliquid

              adipisci, minus rerum optio libero quae provident sed at

              dignissimos, quia nostrum! Fuga dolorum quia hic magni.

            </p>

          </div>

          <div class="tab-pane" id="messages">

            <h4>Messages Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur, adipisicing elit. Fugiat

              quos, at qui aspernatur minus animi hic sunt necessitatibus

              incidunt molestiae reprehenderit ratione neque odit ipsa. Nemo

              laborum consequatur adipisci beatae!

            </p>

          </div>

          <div class="tab-pane" id="settings">

            <h4>Settings Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Minima

              possimus sed odit iste vitae, magnam amet illum laudantium ea!

              Fugiat consectetur consequuntur qui eos obcaecati sequi ipsam

              repellat vero voluptate.

            </p>

          </div>

        </div>

        <!-- Tabs -->

        <ul id="nav-tab" class="nav">

          <li class="active"><a href="#home">Home</a></li>

          <li><a href="#profile">Profile</a></li>

          <li><a href="#messages">Messages</a></li>

          <li><a href="#settings">Settings</a></li>

        </ul>

      </div>

function onTabClick(event) {

  let activeTabs = document.querySelectorAll(".active");



  



  activeTabs.forEach(function(tab) {

    tab.className = tab.className.replace("active", "");

  });



  // activate new tab and panel

  event.target.parentElement.className += " active";

  document.getElementById(event.target.href.split("#")[1]).className +=

    " active";

}



var element = document.getElementById("nav-tab");

element.addEventListener("click", onTabClick, false);

And this is my HTML



<div class="container">

        <!-- Tab panes -->

        <div class="tab-content">

          <div class="tab-pane active" id="home">

            <h4>Home Panel Content</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis.

            </p>

          </div>

          <div class="tab-pane" id="profile">

            <h4>Profile Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Quidem

              iure quos cum, saepe reprehenderit minima quasi architecto numquam

              nesciunt dicta. Qui excepturi recusandae vitae maiores, inventore

              sequi? Rerum, odio omnis. Lorem ipsum dolor sit amet consectetur

              adipisicing elit. Alias distinctio, tempora incidunt aliquid

              adipisci, minus rerum optio libero quae provident sed at

              dignissimos, quia nostrum! Fuga dolorum quia hic magni.

            </p>

          </div>

          <div class="tab-pane" id="messages">

            <h4>Messages Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur, adipisicing elit. Fugiat

              quos, at qui aspernatur minus animi hic sunt necessitatibus

              incidunt molestiae reprehenderit ratione neque odit ipsa. Nemo

              laborum consequatur adipisci beatae!

            </p>

          </div>

          <div class="tab-pane" id="settings">

            <h4>Settings Panel</h4>

            <p>

              Lorem ipsum dolor sit amet consectetur adipisicing elit. Minima

              possimus sed odit iste vitae, magnam amet illum laudantium ea!

              Fugiat consectetur consequuntur qui eos obcaecati sequi ipsam

              repellat vero voluptate.

            </p>

          </div>

        </div>

        <!-- Tabs -->

        <ul id="nav-tab" class="nav">

          <li class="active"><a href="#home">Home</a></li>

          <li><a href="#profile">Profile</a></li>

          <li><a href="#messages">Messages</a></li>

          <li><a href="#settings">Settings</a></li>

        </ul>

      </div>

javascript addeventlistener

asked Nov 11 at 4:00

Igor Voytt

asked Nov 11 at 4:00

Igor Voytt

asked Nov 11 at 4:00

Igor Voytt

asked Nov 11 at 4:00

Igor Voytt

asked Nov 11 at 4:00

Igor Voytt

Works perfectly fine. Press "Run code snippet".
– CertainPerformance
Nov 11 at 4:01

add a comment |

Works perfectly fine. Press "Run code snippet".
– CertainPerformance
Nov 11 at 4:01

Works perfectly fine. Press "Run code snippet".
– CertainPerformance
Nov 11 at 4:01

add a comment |

1 Answer
1

active

oldest

votes

up vote
0
down vote

The problem here is your JavaScript is running before the browser has finished creating those HTML elements. This is because your JavaScript is probably located above your HTML code. There are two ways to fix this. One is to move your JavaScript to just before the closing </body> tag, or the better way is to wrap it in a call to document.addEventListener("DOMContentLoaded", function() {...}); like so:

document.addEventListener("DOMContentLoaded", function() {

    document.querySelectorAll("#nav-tab a").forEach(function(element) {

        element.addEventListener("click", onTabClick, false);

    });

});

The second problem I noticed after I had fixed the first is that since your event handler is applied to the <ul> element, when you get to document.getElementById(event.target.href.split("#")[1]).className += " active";, you will notice that if you clicked on the <ul> element and not one of the links, you would get an error saying Cannot read property 'split' of undefined. Instead, you want to be applying the event listener to the links only, so I have wrapped it in a call to document.querySelectorAll, which will give you just the links, which you can loop over and add event listeners to.

answered Nov 11 at 4:15

Sam Leatherdale

11517

add a comment |

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document.addEventListener("DOMContentLoaded", function() {

    document.querySelectorAll("#nav-tab a").forEach(function(element) {

        element.addEventListener("click", onTabClick, false);

    });

});

answered Nov 11 at 4:15

Sam Leatherdale

11517

add a comment |

up vote
0
down vote

document.addEventListener("DOMContentLoaded", function() {

    document.querySelectorAll("#nav-tab a").forEach(function(element) {

        element.addEventListener("click", onTabClick, false);

    });

});

answered Nov 11 at 4:15

Sam Leatherdale

11517

add a comment |

up vote
0
down vote

document.addEventListener("DOMContentLoaded", function() {

    document.querySelectorAll("#nav-tab a").forEach(function(element) {

        element.addEventListener("click", onTabClick, false);

    });

});

answered Nov 11 at 4:15

Sam Leatherdale

11517

document.addEventListener("DOMContentLoaded", function() {

    document.querySelectorAll("#nav-tab a").forEach(function(element) {

        element.addEventListener("click", onTabClick, false);

    });

});

answered Nov 11 at 4:15

Sam Leatherdale

11517

answered Nov 11 at 4:15

Sam Leatherdale

11517

answered Nov 11 at 4:15

Sam Leatherdale

11517

answered Nov 11 at 4:15

Sam Leatherdale

11517

add a comment |

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