摇一摇js 实现

if (window.DeviceMotionEvent) {
window.addEventListener('devicemotion',deviceMotionHandler, false);
}

var SHAKE_THRESHOLD = 800;
var last_update = 0;
var x, y, z, last_x, last_y, last_z;

function deviceMotionHandler(eventData) {

var acceleration =eventData.accelerationIncludingGravity;
//alert(newDate().getTime());
var curTime = new Date().getTime();

// alert(curTime - last_update);
if ((curTime - last_update)> 300) {

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) {
alert("shaked!");
}
last_x = x;
last_y = y;
last_z = z;
}
}