js 註冊手機搖動事件

var rockModule = (function () {
//監聽手機搖動事件
if (window.DeviceMotionEvent) {
window.addEventListener('devicemotion', deviceMotionHandler, false);
} else {
alert('你的設備不支持DeviceMotion事件');
}
var SHAKE_THRESHOLD = 3000;
var last_update = 0;
var x = y = z = last_x = last_y = last_z = 0;
//搖一搖開關，1表示開，0表示關
var canShake = 1;

function deviceMotionHandler(eventData) {

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

//100ms監聽一次，拒絕重覆監聽
if ((curTime - last_update) > 100 && canShake == 1) {
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) {
canShake = 0;
randomBall();
canShake = 1;
}
last_x = x;
last_y = y;
last_z = z;
}
}
} ());