Posts tagged with valid HTML

Internet Explorer, jQuery, AJAX and HTML5...

Published at March 28, 2011 | Tagged with: , , , , ,

... or how "invalid" HTML can break your JavaScript without a trace

The problem: A few days ago I had the following case. A script that I wrote was working everywhere except in the Internet Explorer(IE) 8 and 7. To be honest I don`t remember the exact error message but when I use the built-in debugger it point me to a row X in jQuery.min.js(those of you who have ever opened a minified JavaScript file know that it is practically unreadable) and not only this, but also provide me with an useless trace-back totally unrelated to the function called. So I decided to start executing the code that break line by line(good for me that I was activated on a "click" so I knew at least where to start).

Speciality: The extra hardness here came from the fact that the problem code was loaded as a result from an AJAX request so the debugger was powerless. So I started with the simplest approach I could imagine - alerting a text/value after every row to see where the error appears. The problem was in the following code:
[sourcecode type="javascript"] $('#my_element').html(data)

Obviously there was something wrong during the execution of the html() method so I started exploring the results from the jQuery selectors. [sourcecode type="javascript"] alert($('container')) // result: [object Object] alert($('container').html) // result: function(a){...} alert($('container').html()) // result: blank (empty string)

I was getting close. The only thing left was to find why the html() method was returning an empty string when I was sure that there was something inside this element(I ran a quick check in FireFox) but I was stuck again.

Investigation: After a few minutes walking in the room later an old issue came to my mind. I ran into it while I was working on a social network project last year. Javascript/jQuery(I didn`t find which one or both) used to act strange when loading invalid HTML with AJAX inside a page under IE.
"Ok, probably a badly closed tag or similar or other fix in a second thing" was my first thought but... unfortunately it turned to be more complex.

Speciality 2: Did I mention it was an HTML5 page? Yeah, I now that IE7&8 does not support HTML5 so we used modernizr but how to recall it on an HTML fragment.

Solution: My favorite StackOverflow come in hand with reloading-modernizr-after-ajax. Following the answer I visited innerShiv, downloaded the plugin and tried again. This time no error but also no reaction on the click - It looked like I was skipping something. Although this it is not explicitly said it looks like that if you don`t pass "false" as second argument of the innerShiv call as in the innershiv jQuery notes the JavaScript code is not executed. I added it and the problem was fixed.

Conclusion: Should I say that I hate IE? Yes, No, Maybe. In the matter of fact I doubt that there is a web developer that uses IE as a primary browser but I have to confess that this time we were both guilty(our developers team and the IE). We used an "invalid code", IE breaks our JavaScript - "eye for an eye" or whatever it is called. The important here is not whose fault it is but to learn from our mistakes. Blaming a two versions old browser is not beneficial to anyone. But this was a good experience and I am sure that I`ll meet this problem again.