Convert object to buffer and buffer to object

Demo

const result =    [
  {                                  // This is sample data BUT there can be multiple objects
    "name": "object1",
    "id": "1",
    "timeseriesData": [
      [
        1548979200000,                // epoc timestamp
        325.3                         // value in number
      ],
      [
        1548979260000,
        325.8
      ],
      [
        1548979320000,
        324.2
      ],
      [
        1548979380000,
        323.7
      ],
      [
        1548979440000,
        322.3
      ],
      [
        1548979500000,
        322
      ]
    ]
  },
  {
    "name": "object2",
    "id": "2",
    "timeseriesData": [
      [
        1548989200000,
        625.3
      ],
      [
        1548989260000,
        625.8
      ],
      [
        1548989320000,
        624.2
      ],
      [
        1548989380000,
        623.7
      ],
      [
        1548989440000,
        622.3
      ],
      [
        1548989500000,
        622
      ]
    ]
  }
]

const splitInChunks = (sizeInBytes) =>   // Don't think this is helping to create proper chunks
    (buffer) => {
        console.log(buffer);
        const size = Buffer.byteLength(buffer.buffer);

        let start = 0;
        let end = sizeInBytes;

        const chunks = [];

        do {
            chunks.push(buffer.subarray(start, end));
            start += sizeInBytes;
            end += sizeInBytes;
        } while (start < size);

        return chunks;
    };
    
   
const chunks = splitInChunks(32)(Buffer.from(JSON.stringify(result)));
console.log("chunks length", chunks.length)
console.log('chunks[0]-', chunks[0])
console.log(JSON.parse(Buffer.concat(chunks)))

For some reason, I want to create buffer of each chunk with some additional data as shownbelow and store it in converted variable. But for some reason, I can't get the original object back from converted varaible.

const converted = chunks.map(c=> Buffer.from(JSON.stringify({requestId:"123", buf: c})));
console.log("converted length", converted.length)
const result1 = [];
for (let con of converted) {
  const eachChunkBuf = JSON.parse(con);
  result1.push(eachChunkBuf.buf)
}
console.log('result1', result1)
console.log(JSON.parse(Buffer.concat(result1)))  // I want result1 to print original object but it doesn't work.

The error in the console indicates that it's the Buffer.concat function which is unhappy, expecting an array of Buffers but instead getting Objects.

I think the error is coming from this bit of your code:

for (let con of converted) {
  const eachChunkBuf = JSON.parse(con);
  result1.push(eachChunkBuf.buf)
}

When you parse the JSON it is not preserving the type of the buffer. So you just need to make sure that eachChunkBuf.buf is in fact a buffer before pushing back to results1.

for (let con of converted) {
  const eachChunkBuf = JSON.parse(con);
  result1.push(Buffer.from(eachChunk.buf));
}