var eg = {};

//获取指定id的元素对象

eg.$ = function (id) {

return document.getElementById(id);

};

//添加事件监听

eg.addListener = function (target, type, handler) {

if (target.addEventListener) {

target.addEventListener(type, handler, false);

} else if (target.attachEvent) {

target.attachEvent("on" + type, handler);

} else {

target["on" + type] = handler;

}

};

//获取指定class名称的元素集合

eg.getElementsByClassName = function (className, element) {

if (document.getElementsByClassName) {

return (element || document).getElementsByClassName(className);

}

var children = (element || document).getElementsByTagName('*');

var elements = new Array();

for (var i = 0; i < children.length; i++) {

var child = children[i];

var classNames = child.className.split(' ');

for (var j = 0; j < classNames.length; j++) {

if (classNames[j] == className) {

elements.push(child);

break;

}

}

}

return elements;

};

//简版AJAX

//config={url:"",type:"get"|"post",async:true|false,data:""}

eg.ajax = function (config, callback) {

var xmlhttp;

if (window.XMLHttpRequest) { //通常非IE浏览器支持XMLHttpRequest对象

xmlhttp = new XMLHttpRequest();

} else if (window.ActiveXObject) { //通常IE浏览器支持ActiveXObject对象

xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); //创建一个低版本对象，msxml组件2.6版本以下支持

if (!xmlhttp) {

xmlhttp = new ActiveXObject("msxml2.XMLHTTP"); //创建一个高版本对象，msxml组件3.0版本以上支持

}

}

if (xmlhttp) {

if (config.async) {

xmlhttp.onreadystatechange = function () { //HTTP状态发生改变时执行

if (xmlhttp.readyState == 4 && xmlhttp.status == 200) { //HTTP请求成功

callback(xmlhttp.responseText, xmlhttp.responseXML);

}

};

//传递参数

xmlhttp.open(config.type, config.url, true);

xmlhttp.send(config.data);

} else {

xmlhttp.open(config.type, config.url, false);

xmlhttp.send(config.data);

callback(xmlhttp.responseText, xmlhttp.responseXML);

}

}

};

//获取元素的页面绝对距顶值

eg.getTop = function (E1) {

var top = 0;

do {

top += E1.offsetTop;

} while ((E1 = E1.offsetParent).nodeName != 'BODY'); //获取到body节点为止

return top;

};