How to Enable XPath in Internet Explorer

2015-02-12T17:13:32+00:00

Yesterday, I shared a little bit about using a virtual machine to test frontend code under Internet Explorer (IE). My goal was to use Wicked Good XPath to add the proper XPath features to IE so that EPUB.js would work correctly, thus making the Philalethes E-Bulletin Online Reader work on all major browsers.

Well, I’d been thinking about this problem for a while, but had delayed working on it because I just didn’t want to fiddle with IE. While I’d been thinking about it, the EPUB.js instructions were updated with IE-specific steps. I didn’t have to look far.

After loading wgxpath.install.js in the header, I just had to add this bit of JavaScript before anything important happened:

// Internet Explorer workaround.
if (!window.XPathResult) {
    EPUBJS.Hooks.register("beforeChapterDisplay").wgxpath = function(callback, renderer){
       wgxpath.install(renderer.render.window);

       if (callback) callback();
    };
    wgxpath.install(window);
}

You can see on line 2 that I test for window.XPathResult instead of looking for a user agent or anything like that. That’s because it’s not really IE I’m interested in detecting. I want to find out if XPath is both available and somewhat standard. User agents are unreliable. Always test for feature availability instead!

The results are good enough for now: the Online Reader works in IE, but it’s not perfect. The cover image doesn’t load full-size and fonts don’t seem to be loading correctly. IE users account for only 10% of the traffic on the website, so obviously I need to work on the EPUB.js cross-browser support. For now, though, it works. And it looks great on Chrome, Safari, and Firefox.

How to Test Your Frontend Against Internet Explorer Without Booting Windows

2015-02-11T19:15:26+00:00

Internet Explorer (IE) has been frustrating me. I want to use stronger words than that, but it would be unprofessional.

I recently launched the Philalethes E-Bulletin Online Reader, which uses EPUB.js and an implementation of XPath that, for some strange reason, isn’t available in IE. I found a few solutions which would work, but all of them require testing in IE. Of course.

This seems like it wouldn’t be a problem, except that I run Linux all the time. All of my work happens on the Linux side of things, so booting into Windows just to run IE for one tiny bug fix is an inconvenience and a chore.

A friend of mine pointed me to modern.IE. Microsoft has graciously released virtual machines usable under MacOS and Linux for running IE and testing. Be warned, however, that the license only lasts 90 days.

I downloaded the 3.5GB virtual machine image and loaded it up in VirtualBox. This might be unusual, but I don’t do a lot of work with virtual machines on my development box. I was immediately greeted with this: [caption id=”attachment_269” align=”aligncenter” width=”530”] Don’t worry, the loading time was a lie. It only took 5 minutes.[/caption]

This solution is not the best for my setup. My computer is getting long in the tooth, so VirtualBox runs neither quickly nor smoothly. However, in this situation, I only needed to test a few lines of code, so it worked.

In my next blog post, which should be coming out shortly, I’ll talk about how I got the Philalethes E-Bulletin Online Reader working for IE.

Erik L. Arneson — Writer and Software Developer

How to Enable XPath in Internet Explorer

How to Test Your Frontend Against Internet Explorer Without Booting Windows