<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Notification</title>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
</head>
<body>
  <header class="header">
    <button id="button" class="btn">Send notification</button>
    <div id="notification" class="notification"></div>
  </header>
  <main>
    <h1>Notification Animation bell</h1>
    <h2>Press the button</h2>
  </main>
</body>

body {
  background-color: #242a37;
  margin: 0;
  font-family: monospace;
  color: #fff;
  text-align: center;
}

.header {
  background-color: #2e3445;
  height: 80px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.btn {
  cursos: pointer;
  background-color: #ed657d;
  color: #f2f2f2;
  text-align: center;
  margin: 5px;
  padding: 15px 35px;
  border: 1px solid transparent;
  border-radius: 4em;
  box-shadow: 5px 5px 4px rgba(0, 0, 0, .2);
  outline: 0;
  transition: .8s:
  will-change: transform;
  z-index: 9999;
}

.btn:active {
  transform: scale(.9);
}

.notification {
  width: 50px;
  height: inherit;
  color: #f2f2f2;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}

.notification::after {
  min-width: 20px;
  height: 20px;
  content: attr(data-count);
  background-color: #ed657d;
  font-family: monospace;
  font-weight: bolt;
  font-size: 14px;
  display: flex;
  justify-content: center;
  align-items: center;
  border-radius: 50%;
  position: absolute;
  top: 5px;
  right: 5px;
  transition: .3s;
  opacity: 0;
  transform: scale(.5);
  will-change: opacity, transform;
}

.notification.show-count::after {
  opacity: 1;
  transform: scale(1);
}

.notification::before {
  content: "\f0f3";
  font-family: "FontAwesome";
  display: block;
}

.notification.notify::before {
  animation: bell 1s ease-out;
  transform-origin: center top;
}

@keyframes bell {
  0% {transform: rotate(35deg);}
  12.5% {transform: rotate(-30deg);}
  25% {transform: rotate(25deg);}
  37.5% {transform: rotate(-20deg);}
  50% {transform: rotate(15deg);}
  62.5% {transform: rotate(-10deg)}
  75% {transform: rotate(5deg)}
  100% {transform: rotate(0);}  
}
const $button = document.getElementById('button');
const $bell = document.getElementById('notification');

$button.addEventListener("click", function(event){
  const count = Number($bell.getAttribute('data-count')) || 0;
  
  $bell.setAttribute('data-count', count + 1);
  $bell.classList.add('show-count');
  $bell.classList.add('notify');
});

$bell.addEventListener("animationend", function(event){
  $bell.classList.remove('notify');
});

External CSS

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External JavaScript

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