I'm developing a web application that support multiple language, and I was asking myself which should be the best tier (if I can name it like that) to check for browser's language.
Should I check it on PHP using $_SERVER["HTTP_ACCEPT_LANGUAGE"] or will be better if I check it in Javascript using navigator.language?
Which and why, stackers?
Actually they will both capture the language set in the browser. The main difference is that the $_SERVER supports multiple languages in order of preference, whereas navigator.language will only be able to select the first language the browser prefers.
Another difference is that one is captured at client side using JavaScript, and the other at the server side using HTTP headers. It is fair to say (even though headers can be spoofed) that capturing the value at the server side is more stable.
Say in Firefox using tools->options->content->language. If I set language to say Chinese
Then when I make a request and examine the HTTP headers it will say:
Accept-Language: zh,en-us;q=0.7,en;q=0.3 //zh is the two letter Chinese representation
and $_SERVER["HTTP_ACCEPT_LANGUAGE"] will give me zh,en-us;q=0.7,en;q=0.3
navigator.language will give me only zh
So in the header you can see that you can support multiple language options in order. So if for some reason Chinese cannot be rendered, you can check for the second language of preference.
If you use navigator.language you cannot do that..
alert(navigator.language) will show en. Now, if I set Chinese as my language in the browser using the steps I mentioned and move it to the top of the language order then alert(navigator.language) will show zh. You can try that too, since it is obvious you don't believe me either :)
You should use the $_SERVER["HTTP_ACCEPT_LANGUAGE"]. Note that this is a weighted list of preferred languages and you should use it accordingly (ie. don't just take the first language off the list)
navigator.language doesn't tell you which is the preferred language set in the browser, but the actual language of the browser application itself.
Edit: from quick testing, the navigator.language returns the preferred language in Firefox, browser language in Opera and Chrome and nothing in IE.
navigator.language, apparently it isn't that way. In most modern browsers, it takes the value from the Accept-Language HTTP header. It can return fr even if your browser is in English.
HTTP_ACCEPT_LANGUAGE is a list of preferred languages, while the navigator.language at best returns just one of them.HTTP_ACCEPT_LANGUAGE is the right way to go as you already state.