javascript模拟实现ajax加载框实例

function loading(p_value,str)

{

if (p_value)

{ 

if (!document.getElementById("load_area"))

{

var para1 = document.createElement("span");

var node=document.createTextNode(str);

para1.appendChild(node);

var para=document.createElement("div");

para.id="load_area"; 

var top=document.body.scrollTop+document.documentElement.scrollTop;//获取页面中的实际高度

top_position = top+157 + "px";

para.style.top =top_position;

icon.style.cssText += ";vertical-align:middle;padding-right:4px;margin-top:-2px;"

para.style.cssText += 

";position:absolute;left:50%;width:140px;margin-left:-70px;height:50px;line-height:50px;font-size:18px;text-overflow:ellipsis;overflow:hidden; white-space:nowrap;text-align:center;background-color: #000;border-radius:2px;-webkit-box-shadow:0 2px 2px rgba(0,0,0,0.5);color:#eee;";
var icon = new Image();

icon.src="images/loading1.gif";//这里用实际路径替换

document.body.appendChild(para);
para.appendChild(icon);

para.appendChild(para1);

}

else

{

document.getElementById("load_area").style.display="block";

}

}

else

{ 

document.getElementById("load_area").style.display="none"; 

}

}

loading(true,"加载中...");  loading(false)