javascript 切换动画

function startMove(obj, json, fn) {
	clearInterval(obj.timer);
	obj.timer = setInterval(function() {
		var bStop = true;
		for (attr in json) {

			var icur = 0;
			icur = (attr == 'opacity') ? Math.round(getStyle(obj, attr) * 100) : parseInt(getStyle(obj, attr));
			var iSpeed = (json[attr] - icur) / 8;
			iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
			if (icur != json[attr]) {
				bStop = false;
			}
			if (attr == 'opacity') {
				obj.style.filter = 'alpha(opacity:' + (icur + iSpeed) + ')';
				obj.style.opacity = (icur + iSpeed) / 100;
			} else {
				obj.style[attr] = icur + iSpeed + 'px';
			}


		}
		if (bStop) {
			clearInterval(obj.timer);
			if (fn) {
				fn();
			}

		}


	}, 30);
}


//获取样式内的属性
function getStyle(obj, attr) {
	if (obj.currentStyle) {
		return obj.currentStyle[attr];
	} else {
		return getComputedStyle(obj, false)[attr];
	}
}