You can compose text here, for transliteration type in textbox bellow.

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Source Code Description

When I was in college, I wrote a quick and dirty code to transliterate in Hindi (DevNagari Script). Much before Google's Implementation. Though my implementation is not very robust, but Its very simple and small. It does not require any internet connection and can work offline.
Note: code was originally written in C#.net and converted to javascript latter. Here is C#.net Code(solution zipped) You need to call function
DoTransLitrate(str) 
Where str--> Phonetically typed (in English) Hindi .
This Function Returns, Hindi Text in Devnagari Script.

Using JavaScript Code

Get the JavaScript File from here include in your html page and call function
Include this script in your page.
<script src="http://www.purplegene.com/static/trans.js" type="text/javascript" language="javascript">
</script>
use this code to use its fuctionality.
var text=DoTransLitrate('yaha meree pustaka hai');
alert(text);