Unexpected end of json input in Node.js

I have Json data which I receive it as post data in my node.js server.

But the problem is, its not able to parse the string I sent.Here is my node.js server code.

res.header("Access-Control-Allow-Origin", "*");
  req.on('data',function(data)
  {
    var done=false;
    console.log(data);
    var schema;

    schema=JSON.parse(data);
   }

Here I get the error when I parse the json data(data).

undefined:776



SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at IncomingMessage.<anonymous> (/Users/as6/Documents/test/server.js:206:17)
    at emitOne (events.js:115:13)
    at IncomingMessage.emit (events.js:210:7)
    at IncomingMessage.Readable.read (_stream_readable.js:462:10)
    at flow (_stream_readable.js:833:34)
    at resume_ (_stream_readable.js:815:3)
    at _combinedTickCallback (internal/process/next_tick.js:102:11)
    at process._tickCallback (internal/process/next_tick.js:161:9)

I verified JSON data using JSONLint for syntax errors.But it was absolutely fine. I dont know what's wrong and how to correct it.