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POsimple iframe based AJAX script: first call yields 'null' element, subsequent call's work perfect. What am I not understanding here?
 

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  1. POsimple iframe based AJAX script: first call yields 'null' element, subsequent call's work perfect. What am I not understanding here?
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    <p>Very simple AJAX script that does the following:</p> <ol> <li>inserts hidden iframe for buffering server side output</li> <li>iframe loads my PHP content silently into a div</li> <li>PHP output is copied from server side div, to parent page div.</li> </ol> <p>The problem is, the first call throws : 'Uncaught TypeError: Cannot set property 'src' of null'. All subsequent calls work perfectly. It's driving me nuts. I love the simplicity of this function but I'm obviously missing something.</p> <p><strong>Javascript called from here:</strong></p> <pre><code>&lt;html&gt; &lt;head&gt; &lt;!-- ajax --&gt; &lt;script src='ajax.js' type='text/javascript'&gt;&lt;/script&gt; &lt;/head&gt; &lt;body&gt; &lt;a href='#' onClick="ajax_request('php.php','show_result');return false;"&gt;get ajax data&lt;/a&gt; &lt;div id='show_result'&gt;&lt;/div&gt; &lt;body&gt; &lt;/html&gt; </code></pre> <p><strong>'ajax.js' file :</strong></p> <pre><code>function ajax_request(url,result_id) { var ajax_iframe_id = 'ajax_iframe_loader'; var ajax_iframe = document.getElementById(ajax_iframe_id); // create hidden iframe transfer buffer if it's not created already. if (ajax_iframe == null) { var element = document.createElement("iframe"); element.setAttribute('src',url); element.setAttribute('id',ajax_iframe_id); document.body.appendChild(element); element.style.display='none'; element.style.width='1'; element.style.height='1'; element.style.border='0'; ajax_iframe = element; } // load server side page into iframe buffer ajax_iframe.src = url; // get the outputted result from inside our transfer div var iframe_inner_doc = ajax_iframe.contentDocument || ajax_iframe.contentWindow.document; var content_to_transfer = iframe_inner_doc.getElementById('to_transfer').innerHTML; // paste result document.getElementById(result_id).innerHTML = content_to_transfer; } </code></pre> <p><strong>'php.php' server script that outputs the result for transfer via AJAX (random number)</strong></p> <pre><code>&lt;html&gt; &lt;body&gt; &lt;div id='to_transfer'&gt;&lt;?=mt_rand(5, 15);?&gt;&lt;/div&gt; &lt;/body&gt; &lt;/html&gt; </code></pre>
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      1. POsimple iframe based AJAX script: first call yields 'null' element, subsequent call's work perfect. What am I not understanding here?
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    1. COplease a snippet where is your ajax_request function called
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      1. POsimple iframe based AJAX script: first call yields 'null' element, subsequent call's work perfect. What am I not understanding here?
      1. USgenesis
    2. COupdated my post.
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      1. POsimple iframe based AJAX script: first call yields 'null' element, subsequent call's work perfect. What am I not understanding here?
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