Walking through Tiddlywiki source (write-up to follow), I noticed some interesting code in TiddlyWiki.js, importTiddlyWiki function.

The code takes a string and injects into an IFrame. I had talked to Jon a little while ago about a similar problem and was wondering about it ever since. The technique here looks like this:

It wraps the text with tags to make it an HTML document: [javascript] var content = “<html><body>” + text + “</body></html>”; [/javascript]

It then introduces a new iframe to the page. [javascript] var iframe = document.createElement(“iframe”); document.body.appendChild(iframe); [/javascript]

Now comes the tricky part. You would think you could just create a new iframe element and set its innerHTML, but with iframes you must use an internal doc ument property. [javascript] var doc = iframe.document; if(iframe.contentDocument) doc = iframe.contentDocument; // For NS6 else if(iframe.contentWindow) doc = iframe.contentWindow.document; // For IE5.5 and IE6 // Put the content in the iframe doc.open(); doc.writeln(content); doc.close(); [/javascript]

Now the content is in our new iframe. We can then manipulate the content using standard Javascript…but ensuring a call like getElementById is executed against the iframe document, not the global document. (i.e. don’t use the usual document.getElementById()). [javascript] // Load the content into a TiddlyWiki() object var storeArea = doc.getElementById(“storeArea”); }; [/javascript]

With this technique, you can take an arbitrary HTML string and delegate its parsing to the browser’s built-in DOM engine.