HTML5 shake 晃动demo

h5-shake.js

```javascript
(function{
	if(window.DeviceMotionEvent) {
		alert('you');
		window.addEventListener('devicemotion', deviceMotionHandler, false);
	}else{
		alert('no');
	}


	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;
		}
	}
})();
```