I know this question is a bit vague and not sure this is even possible. On my web site I want to display a combo box with maximum possible languages (available in unicode) and when the user selects the language respective character map of that language should be loaded. Then users can click and complete the given text area with their comments in their own language. I am not asking for the code but a kind guide line about the possibility of this and a way to do this will be really helpful. My ultimate need is to give user to type in any language of their choice. Do the users need to install the language in their computer before using it? Thank you.
The Unicode Standard does not divide characters by language, and there is no rigorous definition for the concept “characters used in a language”. For example, is “é” a character used in English? (Think about “fiancé”.) What about “è”? (Think about the spelling “belovèd” used in some forms of writing.)
The Unicode Consortium has created the CLDR database, which contains information about “exemplar characters” in any languages, but these are based on subjective judgement and often debatable – mostly in the sense of covering too much, which might not be serious here. The data is in an XML formal, so it could be automatically fed into an application.
There is nothing the user needs to do, or could do, to “install the language” for purposes like this. What matters is whether the user’s computer has fonts containing all the characters needed and whether the browser is able to use them.