Unexpected end of json input in Node.js

Question

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.

try to JSON.stringify first and then check whether it is actually in the right format ? If yes then try this : JSON.parse(JSON.stringify(data)) — Aakash Uniyal
– Aakash Uniyal, Commented Jul 11, 2017 at 9:01

robertklep · Accepted Answer · 2017-07-11 09:09:55Z

38

data events can be fired multiple times, so you have to collect all the data values and concatenate them together when the end event has fires:

let chunks = [];

req.on('data', function(data) {
  chunks.push(data);
}).on('end', function() {
  let data   = Buffer.concat(chunks);
  let schema = JSON.parse(data);
  ...
});

However, perhaps you should consider using body-parser.

answered Jul 11, 2017 at 9:09

robertklep

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2 Comments

mamadgi aishwarya Over a year ago

@robertklep Hey I tried this solution I am getting an error Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client. Can u please help?

robertklep Over a year ago

@mamadgiaishwarya that issue is not strictly related to this question and my answer. If you have could code online somewhere, I'll have a look. Otherwise, search for that error here on SO to find out the cause of it.

Skipper · Accepted Answer · 2018-07-01 14:53:17Z

7

Do change the line

schema = JSON.parse(data);

into

schema = JSON.parse(JSON.stringify(data));

edited Jul 1, 2018 at 14:53

Skipper

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answered Jul 1, 2018 at 13:34

Owais Ibrahim

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1 Comment

Eph Over a year ago

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