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Detailed explanation of the case of obtaining news data using PHP+ajax

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May 16, 2018 am 11:03 AM

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This time I will bring you a detailed explanation of the case of obtaining news data through PHP ajax. What are the precautions for obtaining news data through PHP ajax? The following is a practical case, let's take a look.

The information obtained by the Get method is

string(responseText)

① You can use the JSON object method : stringify() and parse() methods to convert between strings and objects

var arr=[1,2,3];
var a={left:100};
//alert(JSON.stringify(a));//typeof JSON.stringify(arr)是string
//JSON对象的输出有严格格式：&#39;{"left":100}&#39;,变量值要加双引号
var s1="[1,2,3]";
var s2="{left:100}";
var s3=&#39;{"left":100}&#39;;
//alert(JSON.parse(s1));//---输出数组[1,2,3]
//alert(JSON.parse(s2));//---出错。因为JSON对象格式严格，必须是:&#39;{"left":100}&#39;的格式
alert(JSON.parse(s3).left);//---输出Object Object

②Ajax instance of obtaining server content:

getNews.php code:

<?php
header(&#39;content-type:text/html;charset="utf-8"&#39;);
error_reporting(0);
$news=array(
  array("title"=>&#39;习近平同代表委员共商国是两会细节 国平&#39;,"date"=>"2016-3-16"),
   array("title"=>&#39;李克强答如何解决"工资8000元到手仅5000元"&#39;,"date"=>"2016-3-16"),
   array("title"=>&#39;两会闭幕辽宁"老虎"落马曾3年3连跳升副部级&#39;,"date"=>"2016-3-16"),
   array("title"=>&#39;宁波市长卢子跃严重违纪被查 被指行贿斯鑫良&#39;,"date"=>"2016-3-16"),
   array("title"=>&#39;美女翻译六上总理记者会 外号樱桃小丸子&#39;,"date"=>"2016-3-16"),
   array("title"=>&#39;外媒:印尼警方击毙两名中国籍极端分子&#39;,"date"=>"2016-3-16"),
   array("title"=>&#39;复旦将抗肿瘤药物专利6500万美元售美国公司&#39;,"date"=>"2016-3-16"),
 );
echo json_encode($news);

The file getNews.php is displayed in the browser as:

[{"title":"\u4e60\u8fd1\u5e73\u540c\u4ee3\u8868\u59d4\u5458\u5171\u5546\u56fd\u662f\u4e24\u4f1a\u7ec6\u8282 \u56fd\u5e73","date":"2016-3-16"},<span style="font-family: Arial, Helvetica, sans-serif;">{"title":"\u674e\u514b\u5f3a\u7b54\u5982\u4f55\u89e3\u51b3\"\u5de5\u8d448000\u5143\u5230\u624b\u4ec55000\u5143\"","date":"2016-3-16"},</span><span style="font-family: Arial, Helvetica, sans-serif;">{"title":"\u4e24\u4f1a\u95ed\u5e55\u8fbd\u5b81\"\u8001\u864e\"\u843d\u9a6c\u66fe3\u5e743\u8fde\u8df3\u5347\u526f\u90e8\u7ea7","date":"2016-3-16"},{"title":"\u5b81\u6ce2\u5e02\u957f\u5362\u5b50\u8dc3\u4e25\u91cd\u8fdd\u7eaa\u88ab\u67e5\u88ab\u6307\u884c\u8d3f\u65af\u946b\u826f","date":"2016-3-16"},{"title":"\u7f8e\u5973\u7ffb\u8bd1\u516d\u4e0a\u603b\u7406\u8bb0\u8005\u4f1a\u5916\u53f7\u6a31\u6843\u5c0f\u4e38\u5b50","date":"2016-3-16"},{"title":"\u5916\u5a92:\u5370\u5c3c\u8b66\u65b9\u51fb\u6bd9\u4e24\u540d\u4e2d\u56fd\u7c4d\u6781\u7aef\u5206\u5b50","date":"2016-3-16"},{"title":"\u590d\u65e6\u5c06\u6297\u80bf\u7624\u836f\u7269\u4e13\u52296500\u4e07\u7f8e\u5143\u552e\u7f8e\u56fd\u516c\u53f8","date":"2016-3-16"}]

Returns an array, the array elements are 7 JSON objects, each object has two attributes: title and date

What the front end needs to do is to get these data and put them in the corresponding position of the web page through DOM operations.

Ajax: Go to the server to retrieve data through a certain interface (file), and process the retrieved data on the client web page according to the data characteristics.

<body>
    <input id="btn" type="button" value="按钮"/>
    <ul id="ul1">获取新闻到该处</ul>
    <script src="JSON.js"></script>
    <script src="ajax.js"></script>
</body>

xhr.open("get","getNews.php",true);
xhr.setRequestHeader("content-type","application/x-www-form-urlencoded");
xhr.send();
xhr.onreadystatechange=function(){
if(xhr.readyState==4){
  if(xhr.status==200){
    var data=JSON.parse(xhr.responseText);
    varoUl=document.getElementById("ul1");
    var html=&#39;&#39;; //DOM操作，把服务器取回的内容显示在网页上。
    for(var i=0; i<data.length;i++) {
     html+=&#39;<li> <a herf="">&#39;+ data[i].title + &#39;</a> [<span>&#39; + data[i].date + &#39;</span>]</li>&#39;;
   }
    oUl.innerHTML=html;
    }else{
     alert("出错了，Err: " + xhr.status);
    }
  }
}

Page to retrieve data:

③Ajax function simple encapsulation

functionajax(method,url,data,fn){
  try{
    xhr=new XMLHttpRequest();
  }catch(e){
    xhr=newActiveXObject("Microsoft.XMLHTTP");
  }
  if(method == "get" &&data){
    url+=&#39;?&#39;+data;
  }
  xhr.open(method,url,true);
  if(method=="get"){
    xhr.send();
  }else{
    xhr.setRequestHeader("content-type","application/x-www-form-urlencoded")        xhr.send(data);
}
xhr.onreadystatechange=function(){
  if(xhr.readyState==4){
      if(xhr.status==200){
        fn(xhr.responseText);
      }else{
        alert("出错了，Err: " + xhr.status);
      }
    }
  }
}

④ajax wheel Query method to obtain server resources

setInterval(function(){
   ajax(&#39;get&#39;,&#39;getNews.php&#39;,&#39;&#39;,function(data){
      var data=JSON.parse(data);//参数回调
      var oUl=document.getElementById("ul1");
      var html=&#39;&#39;;
      for (var i=0; i<data.length;i++){
        html+=&#39;<li> <aherf="">&#39; + data[i].title + &#39;</a> [<span>&#39; +data[i].date + &#39;</span>] </li>&#39;;
      }
      oUl.innerHTML=html;
    });
},1000);//ajax轮询方式，1秒钟自动更新一次页面。
    //ajax真正的轮询不会1s钟一次那么快，这样太耗资源。

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

Recommended reading:

php shared memory usage and signal control use case analysis

Detailed explanation of vuex operation state object method

Some details in the use of vue components_vue.js

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