Why doesn't jQuery.parseJSON() work on all servers?

Question

Hey there, I have an Arabic contact script that uses Ajax to retrieve a response from the server after filling the form.

On some apache servers, jQuery.parseJS

Answer 1

Found the problem! It was very hard to notice, but I saw something funny about that opening brace... there seemed to be a couple of little dots near it. I used this JavaScript bookmarklet to find out what it was:

javascript:window.location='http://www.google.com/search?q=u+'+('000'+prompt('String?').charCodeAt(prompt('Index?')).toString(16)).slice(-4)

I got the results page. Guess what the problem is! There is an invisible character, repeated twice actually, at the beginning of your output. The zero width non-breaking space is also called the Unicode byte order mark (BOM). It is the reason why jQuery is rejecting your otherwise valid JSON and why pasting the JSON into JSONLint mysteriously works (depending on how you do it).

One way to get this unwanted character into your output is to save your PHP files using Windows Notepad in UTF-8 mode! If this is what you are doing, get another text editor such as Notepad++. Resave all your PHP files without the BOM to fix your problem.

Step 1: Set up Notepad++ to encode files in UTF-8 without BOM by default.

Step 2: Open each existing PHP file, change the Encoding setting, and resave it.