XMLHttpRequest浏览器支持 [英] XMLHttpRequest Browser Support

问题描述

以下代码段在IE7中无法工作的原因是什么？

  var http = new XMLHttpRequest（）; 
 var url ='http://my_site.com/'; 
 var obj = createJsonParamsObj（）; 
 http.open（POST，url，true）; 
 http.setRequestHeader（Content-type，application / x-www-form-urlencoded）; 
 http.send（JSON.stringify（obj））; 
  

从文档中看起来像 new XMLHttpRequest（）应该工作，但有疑问，因为我不能测试它（仅在兼容模式）所以也许我最好使用 new ActiveXObject 。

$ b $

     / * 
为Internet Explorer 5.x-6.x提供XMLHttpRequest构造函数：
其他浏览器（包括Internet Explorer 7.x-9.x）不重新定义
 XMLHttpRequest如果它已经存在。 
 
此示例基于以下发现：
 http://blogs.msdn.com/xmlteam/archive/2006/10/23/using-the-right-version-of- msxml-in-internet-explorer.aspx 
 * / 
 if（typeof XMLHttpRequest ===undefined）{
 XMLHttpRequest = function（）{
 try {return new ActiveXObject （Msxml2.XMLHTTP.6.0）; } 
 catch（e）{} 
 try {return new ActiveXObject（Msxml2.XMLHTTP.3.0）; } 
 catch（e）{} 
 try {return new ActiveXObject（Microsoft.XMLHTTP）; } 
 catch（e）{} 
 // Microsoft.XMLHTTP指向Msxml2.XMLHTTP并且是多余的
 throw new Error（此浏览器不支持XMLHttpRequest。 
}; 
} 
  

或

  / ** 
 *获取XMLHttpRequest。对于Internet Explorer 6，尝试使用MSXML 6.0，
 *然后回退到MXSML 3.0。 
 *如果无法创建对象，则返回null。 
 * @return {XMLHttpRequest或等价的ActiveXObject} 
 * / 
函数getXHR（）{
 if（window.XMLHttpRequest）{
 // Chrome，Firefox，IE7 + ，Opera，Safari 
 return new XMLHttpRequest（）; 
} 
 // IE6 
 try {
 //最新的稳定版本。它具有最好的安全性，性能，
 //可靠性和W3C一致性。与Vista的船，并可用
 //与其他操作系统通过下载和更新。 
 return new ActiveXObject（'MSXML2.XMLHTTP.6.0'）; 
} catch（e）{
 try {
 //后备。 
 return new ActiveXObject（'MSXML2.XMLHTTP.3.0'）; 
} catch（e）{
 alert（'此浏览器未启用AJAX。 
 return null; 
} 
} 
} 
  

参考：http://en.wikipedia.org/wiki/XMLHttpRequest 和http://www.webmasterworld.com/javascript/4027629.htm

Is there a reason the following snippet would not work in IE7?

var http = new XMLHttpRequest();
var url = 'http://my_site.com/';
var obj = createJsonParamsObj();
http.open("POST", url, true);
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.send(JSON.stringify(obj));

From the documentation it seems like the new XMLHttpRequest() should work, but have doubts since I can't test it (only in compatibility mode) so perhaps I better use new ActiveXObject.

解决方案

a small search in google would provide a good answer for your basic problem

/*
   Provide the XMLHttpRequest constructor for Internet Explorer 5.x-6.x:
   Other browsers (including Internet Explorer 7.x-9.x) do not redefine
   XMLHttpRequest if it already exists.

   This example is based on findings at:
   http://blogs.msdn.com/xmlteam/archive/2006/10/23/using-the-right-version-of-msxml-in-internet-explorer.aspx
*/
if (typeof XMLHttpRequest === "undefined") {
  XMLHttpRequest = function () {
    try { return new ActiveXObject("Msxml2.XMLHTTP.6.0"); }
    catch (e) {}
    try { return new ActiveXObject("Msxml2.XMLHTTP.3.0"); }
    catch (e) {}
    try { return new ActiveXObject("Microsoft.XMLHTTP"); }
    catch (e) {}
    // Microsoft.XMLHTTP points to Msxml2.XMLHTTP and is redundant
    throw new Error("This browser does not support XMLHttpRequest.");
  };
}

or

/** 
 * Gets an XMLHttpRequest. For Internet Explorer 6, attempts to use MSXML 6.0,
 * then falls back to MXSML 3.0.
 * Returns null if the object could not be created. 
 * @return {XMLHttpRequest or equivalent ActiveXObject} 
 */ 
function getXHR() { 
  if (window.XMLHttpRequest) {
    // Chrome, Firefox, IE7+, Opera, Safari
    return new XMLHttpRequest(); 
  } 
  // IE6
  try { 
    // The latest stable version. It has the best security, performance, 
    // reliability, and W3C conformance. Ships with Vista, and available 
    // with other OS's via downloads and updates. 
    return new ActiveXObject('MSXML2.XMLHTTP.6.0');
  } catch (e) { 
    try { 
      // The fallback.
      return new ActiveXObject('MSXML2.XMLHTTP.3.0');
    } catch (e) { 
      alert('This browser is not AJAX enabled.'); 
      return null;
    } 
  } 
}

Ref : http://en.wikipedia.org/wiki/XMLHttpRequest and http://www.webmasterworld.com/javascript/4027629.htm

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