How does ajax implement encapsulation of network requests?

This time I will show you how ajax implements network request encapsulation. What are the precautions for ajax to implement network request encapsulation. The following is a practical case, let's take a look.

Example code:

// 封装的ajax网络请求函数
// obj 是一个对象
function AJAX(obj){
    //跨域请求
    if (obj.dataType == "jsonp") {
      //在这里 callback 必须是全局变量 保证函数消失的时候 这个变量不可以被销毁
      //处理一下函数名（防止多个网络请求 函数名字相同 出现紊乱的情况）
      var hehe = "callBack" + "_" + new Date().getTime() + "_" + String(Math.random()).replace(".","");
      window[hehe] = obj.success;
      //创建 script标签
      var sc = document.createElement("script");
      sc.src = obj.url + "?" + "cb=" + hehe;
      console.log(sc.src);
      document.body.appendChild(sc);
      document.body.removeChild(sc);
      return;
    }
 
 
//1、创建 ajax 对象
  var ajaxObj = null;
  if (window.XMLHttpRequest) {
    ajaxObj = new XMLHttpRequest();
  }else{
    ajaxObj = new ActiveXObject("Microsoft.XMLHTTP");
  }
  //设置请求的类型
  obj.type = obj.type.toUpperCase() || "GET";
  //如果是get请求 并且需要传递参数 则需要给 url 后面拼接参数
  if (obj.type == "GET") {
    var arr = [];//定义数组 用于把对象存储到数据里面
    for (var key in obj.data) {
      arr.push(key +"="+ obj.data[key]);
    }
    //用&分隔数组 让其转化为类似：name=lxl&age=18 的形式
    var str = arr.join("&");
    obj.url = obj.url +"?"+ str;
    //拨号
    ajaxObj.open(obj.type,obj.url,true);
    //发送"name=123&age=18"
    ajaxObj.send();
  }else{
    var arr = [];//定义数组 用于把对象存储到数据里面
    for (var key in obj.data) {
      arr.push(key +"="+ obj.data[key]);
      //console.log(arr);
    }
    //用&分隔数组 让其转化为类似：name=lxl&age=18 的形式
    var str = arr.join("&");
    //console.log(str);
    ajaxObj.open(obj.type,obj.url,true);
    ajaxObj.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    ajaxObj.send(str);
  }
  //监听
  ajaxObj.onreadystatechange = function(){
    if (ajaxObj.readyState == 4) {
      if (ajaxObj.status >= 200 && ajaxObj.status < 300 || ajaxObj.status == 304) {
        //请求成功
        obj.success(ajaxObj.responseText);
      }else{
        //请求失败
        obj.error(ajaxObj.status);
      }
    }
  }
}

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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