XMLHttpRequest - Change Value with getElementById
<p>I want the button on the second page to change the value of the button in the first page,this is my code:</p>

<p>FILE 1: Index.html(page one):</p>

<pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd"&gt;

&lt;html lang="en"&gt;
&lt;head&gt;
&lt;meta http-equiv="Content-Type" content="text/html; charset=utf-8"&gt;
&lt;title&gt;Eran Exercise&lt;/title&gt;
&lt;link rel="stylesheet" type="text/css" href="design.css" /&gt;
&lt;script src="new_file.js"&gt;&lt;/script&gt;

&lt;/head&gt;
&lt;body&gt;

    &lt;div class="wrapper"&gt;

        &lt;form&gt; 
&lt;input type="button" id="id200" value="New Window!" onClick="window.open('page2.html','mywindow','width=400,height=200')"&gt; 

&lt;/form&gt; 

                    &lt;/div&gt;


&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>FILE 2:new_file.js(the js file)</p>

<pre><code>function changeLink()
{
var someOtherName="after click";

xmlhttp=new XMLHttpRequest();

xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 &amp;&amp; xmlhttp.status==200)
{
document.getElementById("id200").value = someOtherName;
}
 }
xmlhttp.open("GET","index.php");
xmlhttp.send();
}
</code></pre>

<p>FILE 3:page2.html (page two)</p>

<pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
  "http://www.w3.org/TR/html4/strict.dtd"&gt;

&lt;html lang="en"&gt;
&lt;head&gt;
&lt;script src="new_file.js"&gt;&lt;/script&gt;
 &lt;/head&gt;

&lt;body&gt;
&lt;input type="button" id="id100" onclick="changeLink()" value="Change link"&gt;
&lt;/body&gt;
&lt;/html&gt; 
</code></pre>

<p>Thanks!</p>
