原理：使用DeviceMotion实现，关于DeviceMotion介绍可以查看
https://developer.mozilla.org/en-US/docs/Web/Reference/Events/devicemotion
通过DeviceMotionEvent，可以获得accelerationIncludingGravity的x,y,z属性，根据x,y,z属性的变化来判断设备是否有摇一摇的事件发生。
accelerationIncludeingGravity说明：
The acceleration of the device. This value includes the effect of gravity, and may be the only value available on devices that don’t have a gyroscope to allow them to properly remove gravity from the data.
代码如下：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=utf-8">
<title> html5使用DeviceMotionEvent实现摇一摇 </title>
<style type="text/css">
.center{position:absolute; 640px; height:480px; left:50%; top:50%; margin-left:-320px; margin-top:-240px; line-height:480px; text-align:center; font-size:100px; }
.normal{background:#000000;}
.normal .txt{color:#FFFFFF;}
.doing{background:#FF0000;}
.doing .txt{color:#FFFF00;}
</style>
</head>
<body id="mybody" class="normal">
<div id="txt" class="txt center">请执行摇一摇</div>
</body>
<script type="text/javascript">
var doing = 0; // 判断是否在动画显示中
var speed = 23; // 定义摇动的速度数值
var lastx = 0;
var lasty = 0;
var lastz = 0;
function handleMotionEvent(event) {
var x = event.accelerationIncludingGravity.x;
var y = event.accelerationIncludingGravity.y;
var z = event.accelerationIncludingGravity.z;
if(doing==0){
if(Math.abs(x-lastx)>speed || Math.abs(y-lasty)>speed){
doing = 1;
show();
}
}
lastx = x;
lasty = y;
lastz = z;
}
function show(){
document.getElementById('mybody').className = 'doing';
document.getElementById('txt').innerHTML = '执行了摇一摇';
setTimeout(function(){
doing=0;
document.getElementById('mybody').className='normal';
document.getElementById('txt').innerHTML = '请执行摇一摇';
},3000);
}
window.addEventListener("devicemotion", handleMotionEvent, true);
</script>
</html>