<!DOCTYPE html>
<html lang="en">
<head>
  <title>Bootstrap Example</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.css
">
</head>

<style>body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: white;
}

.button {
  position: relative;
  -webkit-appearance: none;
     -moz-appearance: none;
          appearance: none;
  background: #f72359;
  padding: 1em 2em;
  border: none;
  color: white;
  font-size: 1.2em;
  cursor: pointer;
  outline: none;
  overflow: hidden;
  border-radius: 100px;
}
.button span {
  position: relative;
  pointer-events: none;
}
.button::before {
  --size: 0;
  content: '';
  position: absolute;
  left: var(--x);
  top: var(--y);
  width: var(--size);
  height: var(--size);
  background: radial-gradient(circle closest-side, #4405f7, transparent);
  -webkit-transform: translate(-50%, -50%);
          transform: translate(-50%, -50%);
  transition: width .2s ease, height .2s ease;
}
.button:hover::before {
  --size: 400px;
}
</style>
<body>

<button class="button">
	<span>Hover me I'm awesome</span>
</button>
<script>document.querySelector('.button').onmousemove = function (e) {

	var x = e.pageX - e.target.offsetLeft;
	var y = e.pageY - e.target.offsetTop;

	e.target.style.setProperty('--x', x + 'px');
	e.target.style.setProperty('--y', y + 'px');
};</script>
</body>
</html>

External CSS

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External JavaScript

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