一、基础知识点

1.ajax可以做事情：局部刷新 浏览器搜索列表记录 加载更多的数据

2.登录页面同步网络请求：页面全部刷新，用户量大体验很不好

3.ajax的详解：ajax的get和post请求 同步还是异步，true为异步

ajax.open("get","login.php","true")

二、ajax的get和post请求

2.1 get和post请求

ajax的get异步请求

window.onload = function () {

var btn = document.getElementById('btn');

btn.onclick = function () {

//第一步

var ajax = null;

if(window.XMLHttpRequest){//标准浏览器

ajax = new XMLHttpRequest();

}else{//早期浏览器

ajax = new ActiveXObject('Microsoft.XMLHTTP');

}

var username = document.getElementById('username').value;

var password = document.getElementById('password').value;

//第二步

var geturl = 'open.php?username='+username+'&password='+password;

`post请求加入********`

//var posturl = 'open.php';

//ajax.open('post',posturl,true);

ajax.open('get',geturl,true); //第三步

`post请求加入********`

//ajax.setRequestHeader('Content-Type','application/x-www-form-urlencoded');

//var postParam = 'username='+username+'&password='+password;

//ajax.send(postParam);

ajax.send(null);

//第四步

ajax.onreadystatechange = function () {

if(ajax.readyState == 4){

if(ajax.state == 200){

var data = ajax.responseText;

console.log(data);

}

}

}

}

}

2.2get和post请求区别

***get请求的拼接参数设置

var geturl = 'open.php?username='+username+'&password='+password;

ajax.open('get',geturl,true);

ajax.send(null);

***post请求的参数设置

var posturl = 'open.php';

ajax.open('post',posturl,true);

ajax.setRequestHeader('Content-Type','application/x-www-form-urlencoded');

var postParam = 'username='+username+'&password='+password;

ajax.send(postParam);

2.3后台的返回数据

//后台的数据

$username = $_GET['username'];

$password = $_GET['password'];

$username = $_POST['username'];

$password = $_POST['password'];

//返回的数据echo '用户名:'.$username.'密码:'.$password;

>

三、xml数据解析

3.1数据乱码的解决

var geturl = 'open.php?username='+username+'&password='+password;

变为

var geturl = 'open.php?username='+encodeURIComponent(username)+'&password='+password;

乱码一般是因为出现的中文数据。只需要将中文的数据的前面添加encodeURIComponent进行转码即可。

3.2xml数据解析

张

3

< xing/>

< xing >

李

4

数据解析

var data = ajax.responseText;

var bs = data.getElementsByTagName('xings')[0];

console.log(bs);

var xins = bs.getElementsByTagName('xing');

var tag = '';

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

var xing = xins[i];

var name = xing.getElementsByTagName('name')[0];

var desc = xing.getElementsByTagName('desc')[0];

tag += '

'+getNodeText(name)+''+getNodeText(desc)+',';

}

//展示数据

var tags = document.createElement('tags');

tags.innerHTML = tag;

四、json数据(标准的数据结构类型)解析

json的对象和json的字符串的区别

//json字符串

var str = '{"name":"三国","des":"文学"}';

//将字符串－>json的对象

var data = JSON.parse(str);

//将json的对象－>json字符串

var s = JSON.stringify(data);

//输出的内容为:{"name":"三国","des":"文学"}

console.log(str);

//输出的内容为:文学

console.log(data.des);

//输出的内容为:Object {name: "三国", des: "文学"}

console.log(data);

//输出的内容为:{"name":"三国","des":"文学"}

console.log(s);

4.1 JSON解析的实例讲解

json数据结构

数据实例解析.png

效果图

屏幕快照 2016-07-21 上午10.28.06.png

代码解析

快递

#divcss{

background-color: cornflowerblue;

width: 200px;

height: 200px;

position: relative;

margin-top: 100px;

margin-left: 400px;

}

window.onload = function () {

var btn = document.getElementById('btn');

btn.onclick = function () {

var code = document.getElementById('textfield').value;

//网络请求＊＊＊＊＊＊＊

var ajax = null;

ajax = new XMLHttpRequest();

var url = "https://www.baidu.com";

ajax.open('get',url,true);

ajax.send(nil);

ajax.onreadystatechange = function () {

if(ajax.status == 200&&ajax.readyState == 4){

alert("请求成功");

var data = JSON.parse(ajax.responseText);

if(data.status == 0){

var list = data.data.info.context;

var tag = "";

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

//获取model中的数据

var item = list[i];

var time = item.time;

var desc = item.desc;

var t = new Date();

t.setTime(time+'000');

var str = t.getFullYear()+'年'+(t.getMonth()+1)+'月'+t.getDay()+'日'+(t.getHours()>12?'下午':'上午')+t.getHours()%12+':'+t.getMinutes()+':'+t.getSeconds();

tag += '

';

}

var ul = document.createElement('ul');

ul.innerHTML = tag;

document.getElementById('divcss').appendChild(ul); }

}

};

};

var ul = document.createElement('ul');

ul.innerHTML = "无数据内容";

document.getElementById('divcss').appendChild(ul);

alert(3);

}