按钮水波纹效果

<!DOCTYPE html>  
<html>  
<head>  
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />  
<meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=no">  
<title>html5+ js +css3 点击后水波纹扩散效果 兼容移动端</title>  
  
<style>  
body {margin:0;padding:0;}  
.center{text-align:center}  
  
.btn {position:relative;width:13em;height:3em;margin:2em;border:none;outline:none;letter-spacing:.2em;font-weight:bold;background:#999;cursor:pointer;overflow:hidden;user-select:none;border-radius:2px;color:#fff;}  
button:nth-child(2) {background:#4285f4;}  
button:nth-child(3) {background:#00bad2;}  
button:nth-child(4) {background:#ff8a80;}  
button:nth-child(5) {background:#ffae00;}  
button:nth-child(6) {background:#aec156;}  
button:nth-child(7) {background:#a060a8;}  
button:nth-child(8) {background:#a78660;}  
button:nth-child(9) {background:#5da065;}  
button:nth-child(10) {background:#5e6b9a;}  
button:nth-child(11) {background:#9a5e5e;}  
button:nth-child(12) {background:#666;}  
  
.ripple {position:absolute;background:rgba(0,0,0,.15);border-radius:100%;transform:scale(0);pointer-events:none;}  
.ripple.show {animation:ripple .75s ease-out;}  
@keyframes ripple {to {transform:scale(2);opacity:0;}}  
</style>  
</head>  
<body>  
<h1 class="center">html5 +css3 点击后水波纹扩散效果 兼容移动端</h1>  
<div class="main center">  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
    <button class="btn">BUTTON</button>  
</div>  
<script>  
var addRippleEffect = function (e) {  
    var target = e.target;  
    if (target.className.toLowerCase() !== 'btn') return false;  
    var rect = target.getBoundingClientRect();  
    var ripple = target.querySelector('.ripple');  
    if (!ripple) {  
        ripple = document.createElement('span');  
        ripple.className = 'ripple'  
        rippleripple.style.height = ripple.style.width = Math.max(rect.width, rect.height) + 'px'  
        target.appendChild(ripple);  
    }  
    ripple.classList.remove('show');  
    var top = e.pageY - rect.top - ripple.offsetHeight / 2 - document.body.scrollTop;  
    var left = e.pageX - rect.left - ripple.offsetWidth / 2 - document.body.scrollLeft;  
    ripple.style.top = top + 'px'  
    ripple.style.left = left + 'px'  
    ripple.classList.add('show');  
    return false;  
}  
document.addEventListener('click', addRippleEffect, false);  
</script>  
</body>  
</html>
（兼容移动端）预览地址：http://www.86y.org/demo/ripple/