来自文件的Javascript src取决于域名

I have file http://host1.com/links.txt

links.txt contain:

com http://host1.com/1.jpg
info http://host1.com/2.jpg
org http://host1.com/3.jpg

I need to put in this code src link from that file depending on host domain.

a=document.getElementsByTagName('body')[0];
st='iframe';
r=st;
b=document.createElement(r);
b.src=**Here from links.txt**
b.width=300;b.height=300;b.marginHeight=10;b.marginWidth=10;b.frameborder=10;b.align='left';
a.appendChild(b);

for example I have 3 other sites

1. http://site1.com
2. http://site2.info
3. http://site3.org

In each site index.php I need put that iframe code, and in source code of:

http://site1.com/index.php I must have b.src=http://host1.com/1.jpg

http://site1.info/index.php I must have b.src=http://host1.com/2.jpg

http://site1.org/index.php I must have b.src=http://host1.com/3.jpg

How can I do that?

If you have control over the links.txt and can change it to JSON, you can use JSONP to read it.

You can get the hostname by using window.location.hostname.

links.php

<?php header('content-type: application/json; charset=utf-8'); ?>

(function(){
    var data = {
        com: 'http://host1.com/1.jpg',
        info: 'http://host1.com/2.jpg',
        org: 'http://host1.com/3.jpg'
    };

    <?php echo $_GET['callback']; ?>(data);
})();

javascript

$(function(){
    $.ajax({
       type: 'GET',
        url: 'http://mysite.com/links.php?callback=?',
        async: false,
        jsonpCallback: 'jsonpCallback',
        contentType: "application/json",
        dataType: 'jsonp',
        success: function(json) {
           alert(json.info);
           alert(json.com);
           alert(json.org);
        }
    });
});