Deran Schilling, Learner: January 2011

Sunday, January 02, 2011

Allowing HTML with iFrames and jQuery

So I’ve had a problem of displaying other people’s HTML on my page and their invalid HTML messing up my page’s formatting. So, I found a solution after digging through the Outlook Web Application (OWA) HTML to see how they handle the issue. I do it a little differently, but the idea is the same.

Basically, you have a blank page in an iFrame and you insert the encoded HTML into that blank page. Here’s how I do it:

Setup a blank.htm like this:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title></title>
</head>
<body>
<div id="htmlcontent"></div>
</body>
</html>

Okay, so now on the page you need to display the HTML, you add this:

<iframe id="htmlcontent" frameborder="0" src="/blank.htm" width="600" height="400" style="background: #fff; margin: 0; padding: 0; border: 0">
    <p>Your browser does not support iframes.</p>
</iframe>

Now all we need to do is setup the jQuery like this:

<script language="javascript" type="text/javascript">
    function showHtml(id) {
        $("#htmlcontent").contents().find("#htmlcontent").html($('#' + id).text());
    }
</script>

Now to call the jQuery:

<a href="#" onclick="showHtml('myEncodedHtmlDiv');">Sample Link</a>
<div id="myEncodedHtmlDiv" style="display: none">&lt;p&gt;&lt;strong&gt;Greetings from the Encoded Sample!&lt;/strong&gt;</div>

With ASP.NET, you can do Server.HTMLEncode(htmlToEncode) to encode whatever string you want. The jQuery automatically decodes it when you call the .text() inside the .html() like I did above.

If you want the HTML to show up in a modal, all you need to add is this:

<div id="htmlmsg" style="display: none" class="modal">
<iframe id="htmlcontent" frameborder="0" src="/blank.htm" width="600" height="400" style="background: #fff; margin: 0; padding: 0; border: 0">
    <p>Your browser does not support iframes.</p>
</iframe>
</div>
<div id="overlay" style="display: none"></div>

Here’s the CSS to tag along:

#overlay {position: absolute;
     left: 0px;
     top: 0px;
     width:100%;
     height:100%;
     text-align:center;
     z-index: 1000;
background: #eeeeee 50% 50% repeat; opacity: .80;filter:Alpha(Opacity=80); 
}

.modal { z-index: 10000;
     position: absolute;
     top: 100px;
     margin: 0 auto;
     background: #fff;
     border:1px solid #ccc;
     padding:10px;
     text-align:center
}