Node.js input data event stop

Question

Node.js input data event stop

I use this function to get input data of requests in my Node.js application:

function getData(callback){
  req.data = '';
  req.receivedDataSize = 0;
  req.maxDataSize = 5000;
  req.dataCorrupted = false;

  req.on('data', function(chunk){
    if(req.dataCorrupted === false && chunk.length < req.maxDataSize && req.receivedDataSize < req.maxDataSize){
      req.data += chunk;
      req.receivedDataChunk += chunk.length;
    } else {
       // throw 413 error.

       req.dataCorrupted = true;
       return;
  });

  req.on('end', function(){
    if(req.dataCorrupted === false){
      callback(null);
    } else {
      callback('input-data-corrupted');
    }

    return;
  });
}

I want to know how these "return" statements in each event callback are used, when I throw "return", what will happen on the next "req.on('data') || req.on('end')"? Is there a way to stop the event listener to stop listening to that event, or is just calling "req.end();" a proper way to stop?

javascript
node.js

Answer 1

In your example return doesn't do anything, but end the function and return a value. It doesn't stop the stream from calling back. You can remove those statements completely from your code example and it would work the same.

Calling req.end() should terminate it if it's a stream, which means req.on('data') won't be triggered anymore.

Here's the not super helpful API docs about stream:

http://nodejs.org/api/stream.html#stream_stream_end

This is also a helpful guide to streams in node: http://maxogden.com/node-streams