how to add class in css code example

Example 1: js add class

var element = document.getElementById('element');
element.classList.add('class-1');
element.classList.add('class-2', 'class-3');
element.classList.remove('class-3');

Example 2: javascript add class to element

var someElement= document.getElementById("myElement");
    someElement.className += " newclass";//add "newclass" to element (space in front is important)

Example 3: css class

.myclass {
  border:1px solid black;
  background-color: #d2d2d2;
  height:20px;
  width:60px;
}
/*If you give this class to a div in html, it will get the styles you gave
to that class. You can add multiple classes to a div, and multiple divs
can get that class. */
/* I hope I helped! */

Example 4: css calss

.ThisIsAClassName{
  font-family: sans-serif;
}