Detailed explanation of the use of three ajax parsing modes-JS Tutorial-php.cn

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Detailed explanation of the use of three ajax parsing modes

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Apr 24, 2018 pm 05:12 PM

ajax use model

This time I will bring you a detailed explanation of the use of the three ajax parsing modes. What are the precautions when using the three ajax parsing modes. The following is a practical case, let's take a look.

1. JSON format in Ajax

html code:

<html>
<body>
 <input type="button" value="Ajax" id="btn">
 <script>
  var btn = document.getElementById("btn");
  btn.onclick = function(){
    var xhr = getXhr();
    xhr.open("post","10.php");
    xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
    /*
     * 在客户端如何构建JSON格式
     * * 构建符合JSON格式的字符串
     */
    var user = '{"name":"zhangwuji","pwd":"123456"}';
    xhr.send("user="+user);
    xhr.onreadystatechange = function(){
      if(xhr.readyState==4&&xhr.status==200){
        var data = xhr.responseText;
        /*
         * 使用eval()函数进行转换
         * * 使用"()"将其包裹,eval()函数强制将其转换为JSON格式(javascript代码)
         * * 不使用"()"将其包裹,eval()函数将其识别为一个空的代码块
         */
        var json = eval("("+data+")");
        console.log(json);
      }
    }
  }
  function getXhr(){
    var xhr = null;
    if(window.XMLHttpRequest){
      xhr = new XMLHttpRequest();
    }else{
      xhr = new ActiveXObject("Microsoft.XMLHttp");
    }
    return xhr;
  }
 </script>
 </body>
</html>

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PHP code：

<?php
  // 接收客户端发送的请求数据
  $user = $_POST[&#39;user&#39;];
  // 就是一个JSON格式的string字符串
  //var_dump($user);
  $json_user = json_decode($user,true);
  //var_dump($json_user[&#39;name&#39;]);
  $json = &#39;{"a":1,"b":2,"c":3,"d":4,"e":5}&#39;;
  //var_dump(json_decode($json));
  // 响应数据符合JSON格式的字符串
  // 1. 手工方式构建
  //echo &#39;{"name":"zhouzhiruo","pwd":"123456"}&#39;;
  // 2. 使用json_encode()函数
  echo json_encode($json_user);
?>

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二 XML format in Ajax

html page:

<html>
   <body>
 <input type="button" value="Ajax" id="btn">
 <script>
  var btn = document.getElementById("btn");
  btn.onclick = function(){
    // 实现Ajax的异步交互
    var xhr = getXhr();
    xhr.open("post","07.php");
    xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
    /*
     * 如何构建符合XML格式的请求数据
     * * 注意
     *  * 请求数据的格式 - key=value 不能改变的
     * * 将value值构建成符合XML格式的数据
     *  * 数据类型 - 字符串(string)
     *  * 格式符合XML的语法要求
     * * 编写注意
     *  * 定义变量 - 专门构建XML格式的数据
     *  * 在send()方法进行拼串
     */
    var user = "<user><name>zhangwuji</name><pwd>123456</pwd></user>";
    xhr.send("user="+user);
    xhr.onreadystatechange = function(){
      if(xhr.readyState==4&&xhr.status==200){
        // 接收服务器端的响应数据
        var xmlDoc = xhr.responseXML;
        var nameEle = xmlDoc.getElementsByTagName("name")[0];
        var txtEle = nameEle.childNodes[0];
        console.log(txtEle.nodeValue);
      }
    }
  }
  function getXhr(){
    var xhr = null;
    if(window.XMLHttpRequest){
      xhr = new XMLHttpRequest();
    }else{
      xhr = new ActiveXObject("Microsoft.XMLHttp");
    }
    return xhr;
  }
 </script>
 </body>
</html>

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PHP page code:

<?php
  // 接收客户端发送的请求数据
  $user = $_POST[&#39;user&#39;];//符合XML格式要求的string类型
  //var_dump($user);
  // 创建DOMDocument对象
  $doc = new DOMDocument();
  // 调用loadXML()方法
  $result = $doc->loadXML($user);
  //var_dump($doc);
  // 如何构建符合XML格式的数据
  /* 修改响应头的Content-Type值为"text/xml"
  header('Content-Type:text/xml');
  echo $user;// 符合XML格式的string类型
  */
  header('Content-Type:application/xml');
  echo $doc->saveXML();
?>

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三 HTML format in Ajax

HTML page:

<html>
  <body>
 <select id="province">
  <option>请选择</option>
  <option>山东省</option>
  <option>辽宁省</option>
  <option>吉林省</option>
 </select>
 <select id="city">
  <option>请选择</option>
 </select>
 <script>
  /*
   * 需要思考哪些事情?
   * * 在什么时候执行Ajax的异步请求?
   *  * 当用户选择具体的省份信息时
   */
  // 1. 为id为province元素绑定onchange事件
  var provinceEle = document.getElementById("province");
  provinceEle.onchange = function(){
    // 清空
    var city = document.getElementById("city");
    var opts = city.getElementsByTagName("option");
    for(var z=opts.length-1;z>0;z--){
      city.removeChild(opts[z]);
    }
    if(provinceEle.value != "请选择"){
      // 2. 执行Ajax异步请求
      var xhr = getXhr();
      xhr.open("post","06.php");
      xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
      xhr.send("provcince="+provinceEle.value);
      xhr.onreadystatechange = function(){
        if(xhr.readyState==4&&xhr.status==200){
          // 接收服务器端的数据内容
          var data = xhr.responseText;
          // data是字符串,转换为数组
          var cities = data.split(",");
          for(var i=0;i<cities.length;i++){
            var option = document.createElement("option");
            var textNode = document.createTextNode(cities[i]);
            option.appendChild(textNode);
            city.appendChild(option);
          }
        }
      }
    }
  }
  // 定义创建XMLHttpRequest对象的函数
  function getXhr(){
    var xhr = null;
    if(window.XMLHttpRequest){
      xhr = new XMLHttpRequest();
    }else{
      xhr = new ActiveXObject("Microsoft.XMLHttp");
    }
    return xhr;
  }
 </script>
 </body>
</html>

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php page:

<?php
  // 用于处理客户端请求二级联动的数据
  // 1. 接收客户端发送的省份信息
  $province = $_POST[&#39;provcince&#39;];
  // 2. 判断当前的省份信息,提供不同的城市信息
  switch ($province){
    case &#39;山东省&#39;:
      echo &#39;青岛市,济南市,威海市,日照市,德州市&#39;;
      break;
    case &#39;辽宁省&#39;:
      echo &#39;沈阳市,大连市,铁岭市,丹东市,锦州市&#39;;
      break;
    case &#39;吉林省&#39;:
      echo &#39;长春市,松原市,吉林市,通化市,四平市&#39;;
      break;
  }
  // 服务器端响应的是字符串
?>

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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!

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