How to use native JS to write ajax sample code sharing (collection)

The following editor will bring you an example of writing ajax using native js (recommended). The editor thinks it’s pretty good, so I’ll share it with you now and give it as a reference. Let’s follow the editor and take a look.

The examples are as follows:

// 使用原生js 封装ajax
// 兼容xhr对象
function createXHR(){
  if(typeof XMLHttpRequest != "undefined"){ // 非IE6浏览器
    return new XMLHttpRequest();
  }else if(typeof ActiveXObject != "undefined"){  // IE6浏览器
    var version = [
          "MSXML2.XMLHttp.6.0",
          "MSXML2.XMLHttp.3.0",
          "MSXML2.XMLHttp",
    ];
    for(var i = 0; i < version.length; i++){
      try{
        return new ActiveXObject(version[i]);
      }catch(e){
        //跳过
      }
    }
  }else{
    throw new Error("您的系统或浏览器不支持XHR对象！");
  }
}
// 转义字符
function params(data){
  var arr = [];
  for(var i in data){
    arr.push(encodeURIComponent(i) + "=" + encodeURIComponent(data[i]));
  }
  return arr.join("&");
}
// 封装ajax
function ga_ajax(obj){
  var xhr = createXHR();
  obj.url = obj.url + "?rand=" + Math.random(); // 清除缓存
  obj.data = params(obj.data);   // 转义字符串
  if(obj.method === "get"){   // 判断使用的是否是get方式发送
    obj.url += obj.url.indexOf("?") == "-1" ? "?" + obj.data : "&" + obj.data;
  }
  // 异步
  if(obj.async === true){
    // 异步的时候需要触发onreadystatechange事件
    xhr.onreadystatechange = function(){
      // 执行完成
      if(xhr.readyState == 4){
        callBack();
      }
    }
  }
  xhr.open(obj.method,obj.url,obj.async); // false是同步 true是异步 // "demo.php?rand="+Math.random()+"&name=ga&ga",
  if(obj.method === "post"){
    xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
    xhr.send(obj.data);
  }else{
    xhr.send(null);
  }
  // xhr.abort(); // 取消异步请求
  // 同步
  if(obj.async === false){
    callBack();
  }
  // 返回数据
  function callBack(){
    // 判断是否返回正确
    if(xhr.status == 200){
      obj.success(xhr.responseText);
    }else{
      obj.Error("获取数据失败，错误代号为："+xhr.status+"错误信息为："+xhr.statusText);
    }
  }
}

var html = document.getElementsByTagName("html")[0];
html.onclick = function(){
  ga_ajax({
    "method" : "post",
    "url" : "demo.php",
    "data" : {
      "name" : "gao",
      "age" : 100,
      "num" : "12346&598"
    },
    "success" : function(data){
      alert(data);
    },
    "Error" : function(text){
      alert(text);
    },
    "async" : false
  });
}

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