的XmlHttpRequest - 可以从其他域读JSON？

我已经发现了下面的代码段，它使用XMLHttpRequest来从另一个域读取JSON数据。它的工作原理没有使用JSONP。我认为这是不可能的（http://en.wikipedia.org/wiki/Same_origin_policy）。它为什么有效？的XmlHttpRequest - 可以从其他域读JSON？

<script type="text/javascript"> 
     // Set up the http request object for AJAX calls 
     var http = false; 
     if(navigator.appName == "Microsoft Internet Explorer") http = new ActiveXObject("Microsoft.XMLHTTP"); 
     else http = new XMLHttpRequest(); 

     // Begin by getting partial codelist for all regions in the United Kingdom from the API in JSON format 
     http.open("GET", "http://www.nomisweb.co.uk/api/v01/dataset/nm_1_1/geography/2092957697TYPE480.def.sdmx.json", true); 
     http.onreadystatechange=function() { 
     if(http.readyState == 4 && http.status == 200) { 
      // Evaluate the JSON response 
      var jsonlist = eval("(" + http.responseText + ")"); 

      // String to hold the html for area selection buttons 
      var mycodelist = ''; 

      // Loop through each code in the codelist and build up buttons for the user to click 
      for(i = 0; i < jsonlist.structure.codelists.codelist[0].code.length; i++) 
      { 
      // Get the code value 
      var code = jsonlist.structure.codelists.codelist[0].code[i].value; 

      // Get the description value 
      var desc = jsonlist.structure.codelists.codelist[0].code[i].description.value; 

      // Construct the html for this area button 
      mycodelist += '<input type="button" onclick="getdata(' + code + ',\'' + desc + '\');" value="' + desc + '"><br>'; 
      } 

      // Display the area selections in the "mylist" div 
      document.getElementById('mylist').innerHTML = mycodelist; 
     } 
     } 
     http.send(null); // Make the API request 

    </script>

它适用于Chrome。

http://www2.esd.org.uk/betaesdmapping/1234.HTML

UPDATE

它不工作，在FF 3.6或IE 7

马克西姆

来源

2012-02-09 Maxim Eliseev