解析AJAX中的一些关键技术

//类的构造，传入xml文档和需要处理的标签名称
function DataSet(xmldoc, tagLabel) {
this.rootObj = xmldoc.getElementsByTagName(tagLabel)

//3个方法
this.getCount = getCount
this.getData = getData
this.getAttribute = getAttribute
}
function getCount(){
return this.rootObj.length
}
function getData(index, tagName){
if (index >= this.count) return "index overflow"
var node = this.rootObj[index]
var str = node.getElementsByTagName(tagName)[0].firstChild.data
return str
}

function getAttribute(index, tagName) {
if (index >= this.count) return "index overflow"
var node = this.rootObj[index]
var str = node.getAttribute(tagName)
return str
}
//如何使用DataSet类
function updateByXML(xmlDoc) {

var employeeDS = new DataSet(xmlDoc,"employee"); //关心的标签名称
var count = employeeDS.getCount()
for(i=0;i<count;i++) {
var name = employeeDS.getAttribute(i,"name")
var job = employeeDS.getData(i,"job")
var salary = employeeDS.getData(i,"salary")
alert(name + "," + job + "," + salary)
}
//使用的xml格式，类似如下
<?xml version="1.0" encoding="gb2312"?>
<employees>
<employee name="Billgates">
<job>Programmer</job>
<salary>32768</salary>
</employee>
<employee name="王涛">
<job>无业游民</job>
<salary>70000</salary>
</employee>
<employee name="Big 中华">
<job>哈尔滨CEO</job>
<salary>100000</salary>
</employee>
</employees>

function deleteOldTable() {
delRow = document.getElementsByTagName("table").length
//此句仅在本例中使用，因为本例中已经有一个table了，因此不能删除，需要根据情况变化一下2005.11.17
if(delRow == 1) return

var node = document.getElementsByTagName("table")[delRow-1]; //表格
var c = node.childNodes.length
for(i=0;i<c;i++)
node.removeChild(node.childNodes[0]); //删除全部单元行
}

//传入DataSet的一个实例即可
function makeTable(m_ds) {

deleteOldTable() //先清除以前的结果

var table = document.createElement("table");
table.setAttribute("border","1");
table.setAttribute("width","100%");

document.body.appendChild(table);
var header = table.createTHead();
var headerrow = header.insertRow(0);
headerrow.insertCell(0).appendChild(document.createTextNode("姓名"));
headerrow.insertCell(1).appendChild(document.createTextNode("职业"));
headerrow.insertCell(2).appendChild(document.createTextNode("工资"));

for(var i=0;i<m_ds.getCount();i++) {
var name = m_ds.getAttribute(i,"name")
var job = m_ds.getData(i,"job")
var salary = m_ds.getData(i,"salary")

var row = table.insertRow(i+1);
row.insertCell(0).appendChild(document.createTextNode(name));
row.insertCell(1).appendChild(document.createTextNode(job));
row.insertCell(2).appendChild(document.createTextNode(salary));
}
}