微信页面监听摇一摇事件，并伴有音效

原文出处：http://i.jakeyu.top/2016/05/0...

最近要写一个微信网页，需要监听手机摇动事件，并且伴随有声音

在HTML5，devicemotion事件deviceorientation特性的运动传感器的封装时间装置，你可以通过改变运动时间获取设备的状态，加速和其他数据（有另一个角度deviceorientation事件提供设备，定位等信息）。

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而通过DeviceMotion对设备运动状态的判断，则可以帮助我们在网页上就实现“摇一摇”的交互效果。

把监听事件绑定给 deviceMotionHandler

    if (window.DeviceMotionEvent) {
        window.addEventListener('devicemotion', deviceMotionHandler, false);
    } else {
        alert('本设备不支持devicemotion事件');
    }
    获取设备加速度信息 accelerationIncludingGravity
    
    function deviceMotionHandler(eventData) {
        var acceleration = eventData.accelerationIncludingGravity,
        x, y, z;
        x = acceleration.x;
        y = acceleration.y;
        z = acceleration.z;
        document.getElementById("status").innerHTML = "x:"+x+"<br />y:"+y+"<br />z:"+z;
    }

“摇一摇”的动作既“一定时间内设备了一定距离”，因此通过监听上一步获取到的x, y, z 值在一定时间范围内 的变化率，即可进行设备是否有进行晃动的判断。而为了防止正常移动的误判，需要给该变化率设置一个合适的临界 值。

    var SHAKE_THRESHOLD = 800;
    var last_update = 0;
    var x = y = z = last_x = last_y = last_z = 0;
    
    if (window.DeviceMotionEvent) {
        window.addEventListener('devicemotion', deviceMotionHandler, false);
    } else {
    alert('本设备不支持devicemotion事件');
    }
    
    function deviceMotionHandler(eventData) {
        var acceleration = eventData.accelerationIncludingGravity;
        var curTime = new Date().getTime();
        
        if ((curTime - last_update) > 100) {
            var diffTime = curTime - last_update;
            last_update = curTime;
            x = acceleration.x;
            y = acceleration.y;
            z = acceleration.z;
            var speed = Math.abs(x + y + z - last_x - last_y - last_z) / diffTime * 10000;
            var status = document.getElementById("status");
            
            if (speed > SHAKE_THRESHOLD) {
                doResult();
            }
            last_x = x;
            last_y = y;
            last_z = z;
        }
    }

100毫秒进行一次位置判断，若前后x, y, z间的差值的绝对值和时间比率超过了预设的阈值，则判断设备进行 了摇晃操作。

下面是我改写的代码

    <audio style="display: none;" src="http://xunlei.sc.chinaz.com/files/download/sound1/201410/5018.mp3" id="musicBox" preload="preload"  controls></audio>

    <script>
        var SHAKE_THRESHOLD = 3000;    
        var last_update = 0;    
        var x=y=z=last_x=last_y=last_z=0;   
       var  media; 
       media= document.getElementById("musicBox");
       function init(){
              last_update=new Date().getTime();
               if (window.DeviceMotionEvent) { 
                   window.addEventListener('devicemotion',deviceMotionHandler, false);  
               } else{    
          alert('not support mobile event');
          }
       }
        function deviceMotionHandler(eventData) {    
           var acceleration =eventData.accelerationIncludingGravity; 
           var curTime = new Date().getTime(); 
           if ((curTime - last_update)> 100) {  
                   var diffTime = curTime -last_update;    
                   last_update = curTime;        
                   x = acceleration.x; 
                   y = acceleration.y;   
                   z = acceleration.z;   
                   var speed = Math.abs(x +y + z - last_x - last_y - last_z) / 
           diffTime * 10000;     
                   if (speed > SHAKE_THRESHOLD) {    
                       media.play();
                   }    
                   last_x = x;    
                   last_y = y;    
                   last_z = z;    
               }
        }
        window.onload = function(){
               init();
        }
    </script>