How can I add and remove an active class to an element in pure JavaScript

Question

I am trying to make a navigation menu I did all the HTML and CSS when come to javascript I am struck in the middle I am able to add a class to the

Answer 1

You can use "pure" JavaScript Element.classList to add and remove a class from your DOM element.

add: Add specified class values. If these classes already exist in attribute of the element, then they are ignored.

remove: Remove specified class values.

Use Document.querySelectorAll()to returnsa elements within the document that match the specified group of CSS selectors.

More info at:

https://developer.mozilla.org/en/docs/Web/API/Element/classList

https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelectorAll

Regarding your code, you can mark as active your element when User click on it using the following code:

window.myFunction = function(event) {
  // reset all menu items
  document.querySelectorAll('ul li a.active').forEach(function(item) {
  item.classList.remove('active');
})
  // mark as active selected menu item
  event.target.classList.add("active");
};

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

header {
  width: 100%;
  height: auto;
  max-width: 600px;
  margin: 0 auto;
}

nav {
  width: 100%;
  height: 40px;
  background-color: cornflowerblue;
}

ul {
  list-style-type: none;
}

li {
  display: inline-block;
}

a {
  text-decoration: none;
  padding: 8px 15px;
  display: block;
  text-transform: capitalize;
  background-color: darkgray;
  color: #fff;
}

a.active {
  background-color: cornflowerblue;
}

.active {
  ackground-color: red;
}

  

    

      
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