Internal Anchors

1 April 2007 | 3 Minute Read | Computing

Well, it was an interesting hour that resulted in this…

Facebook notes employ a redirect script for any links found in the note. There is a problem, however, when the link in question contains an apostrophe. The apostrophe is then matched out to its numerical code '.

This was relevant to me since the pictures site has certain URLs containing apostrophes, and the Facebook links were displaying the error page.

Before this error page is shown, I check a number of options to see if the link might be corrected, so I wanted to add a correction for this case. So I thought a simple string replace of ' with ' would work. Nope.

I soon realised that this was because the URL contained a hash, meaning it was pointing to an internal anchor (for example, /path/to/page-with'apostrophe actually went to /path/to/page-with& and tried to find an anchor called 039;apostrophe. So I needed to get the name of the anchor requested as well.

Not possible with PHP. After seeing the explanation in one forum topic, and seeing it clarified in another, I find that the anchor request never actually leaves the browser — it makes the page request, then searches in the result for the anchor. This means that no server-side scripting is going to work.

JavaScript it is, then. Here’s the workaround:

if (!isNaN(parseInt(window.location.hash.substring(1, 2)))) {
    window.location = window.location.href.replace(/&#(d+);/g, function(w, p) {
        return String.fromCharCode(+p);

This matches any case, thanks to TheScripts: since the anchor is CDATA (either through name or id), it must begin with a letter, so only incorrect anchors are checked.

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