var kfc = document.getelementbyid('kf_container');
var z_top = kfc.offsettop;
/*
window.onscroll = function(){
	settimeout('z_zxkf_scroll()',350);
}
*/
var z_zxkf_settimeout = function(){
	settimeout('z_zxkf_scroll()',350);
}
function z_zxkf_scroll(){
	var scrotop, cur_top, step, flag, timer = 80, multiplier = 15, little_step = 8;
	scrotop = document.documentelement.scrolltop || document.body.scrolltop;
	cur_top = kfc.offsettop;
	step = scrotop + z_top - cur_top;//移动距离 = 页面滚动距离 + 客服容器与页面顶部原来的距离 - 客服容器与页面顶部现在的距离
	flag = step > 0 ? 1 : -1;
	step = math.abs(step);
	step = step > little_step*multiplier ? little_step : step/multiplier;
	if(step < 1){
		kfc.style.top = scrotop + z_top + 'px';
	}else{
		kfc.style.top = (cur_top + flag*step) + 'px';
		settimeout('z_zxkf_scroll()',timer);
	}
}

if (navigator.appversion.indexof("msie") != -1){   // ie用attachevent
	window.attachevent('onscroll', z_zxkf_settimeout);           
}else{   // 非ie用addeventlistener
	document.addeventlistener("scroll", z_zxkf_settimeout, false); 
}