问题描述

以下代码段在 IE7 中不起作用是否有原因?

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));

从文档看来， new XMLHttpRequest() 应该可以工作，但我有疑问，因为我无法测试它(仅在兼容模式下)所以也许我最好使用 new ActiveXObject.

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.

推荐答案

在 google 中搜索一下就能很好地解决您的基本问题

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.");
  };
}

或

/** 
 * 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;
    } 
  } 
}

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

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