set disabled with class code example

Example 1: disable whole div bootstrap 4

$("#mydiv").addClass("disabledbutton");
.disabledbutton {
    pointer-events: none;
    opacity: 0.4;
}

Example 2: style disabled button

button:disabled,
button[disabled]{
  border: 1px solid #999999;
  background-color: #cccccc;
  color: #666666;
}