Is it possible to perform an asynchronous cross-domain file-upload?

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醉话见心 2020-12-02 06:06
It is possible! Read below.

First of all, let me use this diagram to explain how asynchronous file uploads can be achieved:
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爱一瞬间的悲伤 (楼主)
2020-12-02 06:33
The following approach is working in my setup (Firefox 3.6):



<!-- get data from iframe after load and process them --> 
<script type="text/javascript">
    function process(iframe) {
       var data = iframe.contentWindow.document.body.innerHTML; 
       // got test data="<xml><a>b</a></xml>"
    }
</script>
</code></pre>

<p>It is working in Chrome as well, but it is needed to exclude a first onload call after the loading of the parent page. This is easily accomplished by setting a "global" variable which is tested in <code>process()</code>.</p>

<p><strong>ADDITION</strong> </p>

<p>The method works together with a form</p>

<pre><code><form action="URL" method="post" enctype="multipart/form-data" target="load_target">
</code></pre>

<p>which is submitted to <code>URL</code>. This <code>URL</code> needs to reside on the same domain as the parent page <code>page.html</code>. If data from a <code>REMOTE_URL</code> are to be downloaded, then <code>URL</code> would be a PHP <code>proxy.php</code> on the own domain with the content</p>

<pre><code><?php echo file_get_contents("REMOTE_URL"); ?>
</code></pre>

<p>This is a simple approach - however, it is probably excluded by the condition (2) of the question. I have added it here to make my answer complete. </p>

<p>Other approaches, considering iframes only, are discussed by Mahemoff and Georges Auberger.</p>
    </p>
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