How to implement DedeCMS digg Ajax cross-domain

visitCountCallBack({ 
"visitcount":135 
});

You can copy the above code to your local computer and open it with IE or FIREFOX. Click the button. I found that the dynamic effect was achieved without refreshing the page, and the returned data was obtained across domains. Everyone knows that JAVASCRIPT cannot be accessed across domains, which is amazing. . . . Careful study of the code revealed the wonders

This code:

 var s = document.createElement("SCRIPT"); 
s.id="cgi_emotion_list"; 
document.getElementsByTagName("HEAD")[0].appendChild(s); 
s.src="http://g2.qzone.qq.com/fcg-bin/cgi_emotion_list.fcg?uin=123456";

The browser obtained the SCRIPT element through DOM parsing, and then added the ID and SRC attributes. Here is the official explanation of the SRC attribute of the SCRIPT element from the W3C specification: The script element allows authors to include dynamic script in their documents. When the src attribute is set, the script element refers to an external file. The value of the attribute must be a URI (or IRI). If the src attribute is not set, then the script is given by the contents of the element. Interpreted as: If the SRC attribute of the SCRIPT tag is defined, the SCRIPT tag refers to an external file, and the attribute value Must be a URL. This means that SCRIPT will reference the contents of the file from this URL. Everyone accesses this link in the browser: http://g2.qzone.qq.com/fcg-bin/cgi_emotion_list.fcg?uin=123456 This URL similar to JAVA's SERVLET returns the following data: visitCountCallBack({"visitcount": 65188579, "dayvisit":8658, "spacemark":0, "markchange":0, "sun":1680, "love":478, "rain":1680, "nutri":1450, "level":5, "gardener":1});This string is a JAVASCRIPT function, and the input is a JSON string. When this data is returned, another JAVASCRIPT function above is called: function visitCountCallBack(data){

document.getElementsByTagName("HEAD")[0].removeChild(document.getElementById("cgi_emotion_list")); 
for(var i in data){ 
var e =document.getElementById(i); 
if(e) e.innerHTML=data[i]; 
} 
}

In the function, the JSON data returned by the innerHTML bar is used to fill the BODY, achieving asynchronous access to the data without refreshing the page. Effect. There is another key question: http://g2.qzone.qq.com/fcg-bin/cgi_emotion_list.fcg?uin=123456 is a URL of QQ space (uin is QQ number, you can enter your own QQ number to try (Test), JAVASCRIPT calls data from other domains. This method is relatively simple to obtain data, and can also access data across domains. It is more suitable for some simple, small non-refresh effects. I am a little worried that if the browser is updated one day and denies this access method, the data obtained in this way may become unusable. I suggest that everyone use this method with caution! ! !

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