Passing a Text Stream from NodeJS to Browser

Question

I am trying to stream a text file processed in NodeJS to a browser.
The following is the text file before processing.
The file is named dbUsers.json.

{"userId":443,"email":"[email protected]","hashedPassword":"36583a77a098c02ef111e2f2521d77b58e420f2bc7e9bf930ec24b21d42ea2e0","timeStamp":1567439821109,"deleted":false}
{"userId":447,"email":"[email protected]","hashedPassword":"36583a77a098c02ef111e2f2521d77b58e420f2bc7e9bf930ec24b21d42ea2e0","timeStamp":1567439909013,"deleted":false}
{"userId":451,"email":"[email protected]","hashedPassword":"36583a77a098c02ef111e2f2521d77b58e420f2bc7e9bf930ec24b21d42ea2e0","timeStamp":1567443638340,"deleted":false}
...

After processing I am able to stream the data to a new file on the NodeJS server with the following commands:

// Create a writable stream and specify the file which will receive the data from the readable stream.
let destinationStream = fs.createWriteStream(_data.baseDir + '/dbPermissions/dbUsers' + '/' + 'test' + '.txt', {flags : 'a'});


pipeline
(
  sourceStream,
  destinationStream,
  function(error){if(error){console.log('There was an error.');}}
);

The new file shows the data processed as expected.
Some fields have been deleted and the records marked for deletion have been removed.
This demonstrates that sourceStream is functioning within NodeJS.
The data in the new file is now as follows:

{"userId":443,"email":"[email protected]","timeStamp":1567439821109}
{"userId":447,"email":"[email protected]","timeStamp":1567439909013}
{"userId":451,"email":"[email protected]","timeStamp":1567443638340}
...

Logging sourceStream to the NodeJS console before streaming it to the client browser produces the following output.

Readable {
  _readableState:
   ReadableState {
     objectMode: false,
     highWaterMark: 16384,
     buffer: BufferList { head: [Object], tail: [Object], length: 45 },
     length: 3035,
     pipes:
      WriteStream {
        _writableState: [WritableState],
        writable: true,
        domain: null,
        _events: [Object],
        _eventsCount: 6,
        _maxListeners: undefined,
        path:
         'C:\\Users\\user\\Desktop\\Tutorials\\iotajs\\ias\\accounting\\/dbPermissions/dbUsers/test.txt',
        fd: null,
        flags: 'a',
        mode: 438,
        start: undefined,
        autoClose: true,
        pos: undefined,
        bytesWritten: 0,
        closed: false },
     pipesCount: 1,
     flowing: true,
     ended: true,
     endEmitted: false,
     reading: false,
     sync: true,
     needReadable: false,
     emittedReadable: true,
     readableListening: false,
     resumeScheduled: true,
     paused: false,
     emitClose: true,
     destroyed: false,
     defaultEncoding: 'utf8',
     awaitDrain: 0,
     readingMore: true,
     decoder: null,
     encoding: null },
  readable: true,
  domain: null,
  _events:
   [Object: null prototype] {
     close: [ [Function], [Function: onclose] ],
     end: [ [Function: onend], [Function] ],
     finish: [Function: onfinish],
     error: [Function: onerror],
     data: [Function: ondata] },
  _eventsCount: 5,
  _maxListeners: undefined }
Returning this response:  200
Returning this response:  200

When streaming sourceStream to the browser and then logging out to the browser's console, the output is the same as above.
So I am sure that sourceStream is getting to the client intact.

The data I need to work with is probably locked up in the many buffer properties of the object above, now called responseTextStream on the client browser.

My problem is that I don't know how to access the information in the buffers nor do I know how to convert them from numbers back into text.

The following is the function in the client browser where I am hoping to use the data in the buffers. This is where I need help - I don't know how to access the stream. Thanks, John

// Populate the dbUsersList webpage with user records.
app.loadUsersListPage = function()
{  
  // Ask the server for the JSON records found in the dbUsers file.
  // Then run the callback function defined here which inserts rows into the usersListTable on the webpage
  // and populates them with data from the file of JSON records returned.
  app.client.request(undefined,'api/aUsers','GET',QueryStringObject,undefined,function(statusCode,responseTextStream)
  {
    // if the call to handlers._users.get which is mapped to api/aUsers called back success.
    if(statusCode == 200) 
    {
      // The streamed data can be seen on the console as a buffer full of numbers
      console.log(responseTextStream._readableState.buffer.head.data.data);

      // Create a handle which can be used to manipulate the table on the webpage.
      var table = document.getElementById("usersListTable");


      // The pseudocode below does not work but is shows what I hope to accomplish. 
      // The line below does not help to access the stream. This is where I need help.
      // What line or lines of code would facilitate access to the stream and allow 
      // processing it as a string, character by character, as shown below.
      var Astr = responseTextStream;

      var line = "";

      for(var i=0; i<Astr.length; i++)
      {
        var chr = String.fromCharCode(Astr[i]);
        if(chr == "\n" || chr == "\r")
        {
          // Look at each line of json at the console as it is consumed.
          console.log("line: ",line);

          // Turn the line, which is a json string, back into a json object 
          var recordObject = JSON.parse(line);

          if(recordObject)
          {
            // Insert a new row in the table.
            var tr = table.insertRow(-1);
            // Make the new row a member of the class 'checkRow'
            tr.classList.add('checkRow');

            // Insert five new cells into the new row.
            var td0 = tr.insertCell(0);
            var td1 = tr.insertCell(1);
            var td2 = tr.insertCell(2);   
            var td3 = tr.insertCell(3);          

            // load the new cells with data from the recordObject.
            td0.innerHTML = recordObject.userId;      
            td1.innerHTML = recordObject.email;
            td2.innerHTML = recordObject.timeStamp;      
            td3.innerHTML = '<a href="/users/edit?email=' + recordObject.userId + '">View / Edit / Delete</a>';
          } // End of: if(recordObject)

          // clear the line buffer to start the next line.
          line = "";

        } // End of: if(chr == "\n" || chr == "\r"){do stuff}
        else 
        {
            line += chr;
        }           

      }; // End of: for(var i=0; i<Astr.length; i++){...}

    } // End of: if the call to handlers._users.get which is mapped to api/aUsers called back successfully.

  }); // End of: app.client.request(undefined,'api/checks','GET'...

} // End of: app.loadUsersListPage = function(){...}
// End of: Populate the dbUsersList webpage with user records.

According to the answer from @Brad I used his code with the same unsatisfactory result. Below is Brad's code and below that is the object that is returned by his code at the point where value is logged to the console. It's the same object as before with the buffers expanded for examination. My problem remains that the returned object is just a bunch of buffers that contain a bunch of numbers and not strings that I can do something with. When logging value to the console I am hoping to see each line of the modified data in human readable format. What am I not doing, or what am I doing wrong? Thanks, John

// Populate the dbUsersList webpage with user records.
app.loadUsersListPage = async function()
{  
  // Define which users will be retrieved from dbUsers.json
  // This is not being used for now so all records will be retrived.
  var QueryStringObject = {};

  // Define a client function that calls for data from the server.
  const fetchPromise = fetch('api/aUsers')
  .then
  (
    (res) => 
    {
      // Verify that we have some sort of 2xx response that we can use
      if (!res.ok) 
      {
        throw res;
      }

      // If no content, immediately resolve, don't try to parse JSON
      if (res.status === 204) 
      {
        return;
      }

      // Initialize variable to hold chunks of data as they come across.
      let textBuffer = '';

      // This does not seem to be used. Delete this after everything else is working.
      const self = this;

      // Process the stream.
      return res.body

      // Decode as UTF-8 Text
      .pipeThrough
      (
        new TextDecoderStream()
      )

      // Split on lines
      .pipeThrough
      (
        new TransformStream
        (
          {
            transform(chunk, controller) 
            {
              textBuffer += chunk;

              const lines = textBuffer.split('\n');

              for (const line of lines.slice(0, -1)) 
              {
                controller.enqueue(line);
              } // End of: for (const line ...)

              textBuffer = lines.slice(-1)[0];
            }, // End of: Transform(chunk, controller){do stuff}

            flush(controller) 
            {
              if (textBuffer) 
              {
                controller.enqueue(textBuffer);
              } // End of: if (textBuffer)
            } // End of: flush(controller){do stuff}
          } // End of: parameters for new TransformStream
        ) // End of: call to constructor new TransformStream
      ) // End of: parameters for pipeThrough - Split on lines

      // Parse JSON objects
      .pipeThrough
      (
        new TransformStream
        (
          {
            transform(line, controller) 
            {
              if (line) 
              {
                controller.enqueue
                (
                  JSON.parse(line)
                ); //End of: call to controller.enqueue function
              } // End of: if (line)
            } // End of: transform function
          } // End of: parameter object for new TransformStream
        ) // End of: new TransformStream parameters
      ); // End of: parameters for .pipeThrough - Parse JSON objects
    } // End of: .then callback function instruction for fetch
  ); // End of: .then callback parameters for fetch


  // Call to function which asks server for data.
  const res = await fetchPromise;

  const reader = res.getReader();

  function read() 
  {
    reader.read()
    .then
    (
      ({value, done}) => 
      {
        if (value) {
          // Your object will be here
          console.log('I got to this point');
          console.log(value);
        }
        if (done) {
          return;
        }
        read();
      }
    );
  }

  read();

} // End of: app.loadUsersListPage = function(){...}
// End of: Populate the dbUsersList webpage with user records.

This is what I get when Brad's code logs value to the console. It is the same thing I got before. I was hoping to see lines of text. What am I not doing, or what am I doing wrong? Thanks, John

{_readableState: {…}, readable: true, domain: null, _events: {…}, _eventsCount: 0}
domain: null
readable: true
_events: {}
_eventsCount: 0
_readableState:
awaitDrain: 0
buffer:
head:
data:
data: (65) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 52, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 98, 111, 98, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 51, 57, 56, 50, 49, 49, 48, 57, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 52, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 97, 108, 105, 99, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 51, 57, 57, 48, 57, 48, 49, 51, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 53, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 99, 108, 105, 102, 102, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 52, 51, 54, 51, 56, 51, 52, 48, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 53, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 97, 114, 103, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 52, 51, 55, 54, 53, 54, 48, 57, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 53, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 99, 108, 105, 110, 116, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 52, 51, 56, 49, 51, 49, 54, 55, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 54, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 98, 121, 114, 111, 110, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 52, 51, 57, 52, 50, 48, 57, 54, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 54, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 105, 108, 116, 111, 110, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 52, 52, 50, 48, 55, 53, 52, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 55, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 97, 114, 110, 111, 108, 100, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 52, 52, 52, 50, 51, 57, 55, 53, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 55, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 115, 97, 108, 108, 121, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 52, 56, 57, 56, 57, 52, 54, 57, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 57, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 97, 114, 118, 105, 110, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 53, 48, 51, 56, 50, 52, 54, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 57, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 110, 97, 110, 99, 121, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 53, 48, 52, 49, 55, 52, 52, 57, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 52, 57, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 102, 114, 101, 100, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 53, 48, 52, 51, 48, 55, 52, 50, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 48, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 97, 108, 101, 120, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 52, 53, 52, 56, 55, 57, 55, 53, 51, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 48, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 104, 101, 114, 109, 97, 110, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 53, 48, 54, 48, 50, 55, 50, 49, 55, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (69) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 49, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 97, 114, 103, 114, 101, 116, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 53, 53, 55, 53, 50, 49, 51, 55, 51, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (69) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 49, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 115, 121, 110, 116, 104, 105, 97, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 53, 53, 55, 53, 55, 51, 56, 52, 48, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 49, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 99, 111, 110, 110, 101, 114, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 53, 53, 55, 54, 48, 55, 51, 56, 55, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 50, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 97, 114, 103, 111, 116, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 55, 53, 53, 56, 53, 57, 57, 50, 48, 48, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 50, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 100, 101, 110, 105, 115, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 48, 54, 54, 50, 56, 55, 53, 54, 48, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 51, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 112, 104, 105, 108, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 48, 54, 54, 56, 49, 50, 48, 55, 48, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 51, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 111, 114, 103, 97, 110, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 48, 55, 55, 53, 55, 55, 56, 53, 56, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 51, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 108, 117, 107, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 48, 55, 50, 53, 48, 49, 51, 55, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 52, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 119, 97, 114, 114, 101, 110, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 48, 56, 52, 55, 50, 54, 56, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 53, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 119, 105, 108, 98, 117, 114, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 49, 49, 49, 56, 54, 51, 55, 54, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 53, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 112, 97, 117, 108, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 49, 49, 50, 50, 52, 55, 57, 49, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (70) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 53, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 102, 108, 111, 114, 97, 110, 99, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 53, 50, 50, 48, 48, 51, 50, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (69) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 54, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 117, 109, 102, 111, 114, 100, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 53, 50, 51, 55, 53, 57, 56, 50, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 54, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 98, 97, 114, 116, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 53, 55, 55, 48, 49, 57, 55, 49, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 55, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 104, 111, 109, 101, 114, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 53, 55, 55, 57, 48, 53, 49, 53, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (69) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 55, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 102, 97, 108, 107, 110, 101, 114, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 54, 51, 48, 52, 55, 52, 53, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (70) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 55, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 97, 110, 100, 101, 114, 115, 111, 110, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 57, 54, 51, 56, 53, 50, 53, 51, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 56, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 98, 97, 114, 114, 121, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 49, 57, 55, 55, 52, 54, 48, 55, 51, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 56, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 98, 97, 114, 110, 101, 121, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 50, 51, 54, 54, 52, 54, 54, 54, 50, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 57, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 98, 101, 116, 116, 121, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 50, 51, 54, 55, 52, 57, 54, 51, 54, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 57, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 115, 116, 101, 118, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 50, 52, 52, 56, 49, 56, 48, 50, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 53, 57, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 115, 104, 105, 114, 108, 121, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 50, 56, 49, 54, 49, 54, 50, 53, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 48, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 97, 103, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 50, 56, 49, 56, 57, 54, 52, 50, 55, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (71) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 48, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 99, 111, 110, 115, 116, 97, 110, 99, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 50, 48, 54, 56, 49, 53, 54, 54, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (68) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 49, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 109, 97, 114, 115, 104, 97, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 50, 48, 56, 55, 55, 57, 56, 54, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 49, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 103, 114, 101, 103, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 50, 49, 49, 53, 55, 49, 56, 53, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 50, 51, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 112, 101, 116, 101, 114, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 50, 49, 50, 48, 55, 55, 51, 55, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (67) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 50, 55, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 99, 105, 110, 100, 121, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 56, 52, 52, 52, 49, 52, 54, 49, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 51, 49, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 114, 111, 115, 101, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 56, 52, 52, 55, 50, 49, 48, 57, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (66) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 51, 53, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 98, 97, 114, 98, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 56, 52, 53, 51, 57, 52, 50, 52, 125, 10]
type: "Buffer"
__proto__: Object
next:
data:
data: (69) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 51, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 103, 105, 108, 98, 101, 114, 116, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 56, 52, 53, 57, 56, 56, 54, 55, 125, 10]
type: "Buffer"
__proto__: Object
next: null

length: 45
tail:
data:
data: (69) [123, 34, 117, 115, 101, 114, 73, 100, 34, 58, 54, 51, 57, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 103, 105, 108, 98, 101, 114, 116, 64, 103, 109, 97, 105, 108, 46, 99, 111, 109, 34, 44, 34, 116, 105, 109, 101, 83, 116, 97, 109, 112, 34, 58, 49, 53, 54, 56, 52, 56, 52, 53, 57, 56, 56, 54, 55, 125, 10]
type: "Buffer"
__proto__: Object
next: null

I did not include the entire object.

As seen above, many buffers are contained in the object returned. I think each buffer contains a line/record from the original dbUsers file with some fields removed and duplicate records deleted. I would like to see these buffers as human readable text. Because many buffers are being returned, eventually I will need to learn how to iterate through the buffers but for now I am just trying turn the first buffer into text. Brad at this point is at a disadvantage because he is not near a computer. So he can not see the code I am using. In any case, he kindly advised me to try the toString() function. So I tried the following line of code on the first buffer. console.log(value._readableState.buffer.head.data.data.toString()); The following numbers were the result. I was hoping for a string of text. Can anyone see what I am failing to do? Thanks, John

123,34,117,115,101,114,73,100,34,58,52,52,51,44,34,101,109,97,105,108,34,58,34,98,111,98,64,103,109,97,105,108,46,99,111,109,34,44,34,116,105,109,101,83,116,97,109,112,34,58,49,53,54,55,52,51,57,56,50,49,49,48,57,125,10

After trying the following line of code I am still getting numbers not letters at the console. console.log(value._readableState.buffer.head.data.data.toString('utf8')); Thanks, John

Answer 1

Since you're using Chrome, you get to use all the new goodness like TextDecoderStream and TransformStream in a nifty pipeline that streams data from the HTTP response and decodes that line-delimited JSON as it does it. Check this out:

const fetchPromise = fetch(url, params).then((res) => {
  // Verify that we have some sort of 2xx response that we can use
  if (!res.ok) {
    throw res;
  }

  // If no content, immediately resolve, don't try to parse JSON
  if (res.status === 204) {
    return;
  }

  let textBuffer = '';

  const self = this;

  return res.body
    // Decode as UTF-8 Text
    .pipeThrough(new TextDecoderStream())

    // Split on lines
    .pipeThrough(new TransformStream({
      transform(chunk, controller) {
        textBuffer += chunk;
        const lines = textBuffer.split('\n');
        for (const line of lines.slice(0, -1)) {
          controller.enqueue(line);
        }
        textBuffer = lines.slice(-1)[0];
      },
      flush(controller) {
        if (textBuffer) {
          controller.enqueue(textBuffer);
        }
      }
    }))

    // Parse JSON objects
    .pipeThrough(new TransformStream({
      transform(line, controller) {
        if (line) {
          controller.enqueue(
            JSON.parse(line)
          );
        }
      }
    }));
});

Now, you can consume this new object stream like any other:

  const res = await fetchPromise;
  const reader = res.getReader();
  function read() {
    reader.read().then(({value, done}) => {
      if (value) {
        // Your object will be here
      }
      if (done) {
        return;
      }
      read();
    });
  }
  read();

(Note: I haven't tested this code in this example context... I modified this from one of my projects, so please look it over and adapt it for your specific purposes.)