nodejs chunk garbled code

When using node.js to upload or download files, we usually encounter the problem of chunk garbled characters. The so-called chunk refers to a data block. When we transfer or download a file, the file will be divided into small pieces of data for transmission. This block transmission method can reduce transmission time and traffic and improve the efficiency of file transmission. However, during the block transmission process, if we do not correctly encode and decode the data blocks, garbled characters will occur.

Before dealing with the chunk garbled problem, we need to understand several concepts first. The first is encoding and decoding. Encoding is the process of converting text in a character set into binary data that a computer can process, while decoding is the process of converting binary data back to text in the original character set. Commonly used encoding formats include ASCII encoding, UTF-8 encoding, etc. In node.js, Buffer objects are used for encoding and decoding operations.

The second is flow. In node.js, a stream is an abstract concept that divides data into chunks for processing. When transferring files through streams, the data is divided into blocks for data stream transmission, which can reduce memory pressure and improve program performance. In node.js, commonly used streams include readable stream (Readable), writable stream (Writable), readable and writable stream (Duplex), etc.

The last one is chunk. In node.js, a chunk refers to a small piece of data in a stream. During the chunked transfer process, the server divides the file into several chunks for data transmission, and the client receives these chunks from the server and combines them into a complete file.

When the chunk contains non-ASCII characters, if we do not perform the correct encoding and decoding operations, the chunk will be garbled. When we use the res.write method to return chunk data, we need to perform the correct encoding operation on the data, for example:

const str = "中文";
res.write(Buffer.from(str, "utf-8"));

The first parameter is the string to be encoded, and the second parameter is the encoding. Format. For Chinese character sets, UTF-8 encoding is generally used. This way we can correctly encode and send the data chunk to the client.

When receiving and processing chunk data, we also need to perform appropriate decoding operations, such as:

let data = "";
res.on("data", chunk => {
  // 拼接接收到的数据
  data += chunk;
});

res.on("end", () => {
  // 将数据解码为字符串
  const str = Buffer.from(data, "base64").toString("utf-8");
});

After receiving the chunk data, we need to splice the data together and After the data transmission is completed, the data is decoded into string format. In addition, the correct decoding format needs to be specified when decoding.

To sum up, correct encoding and decoding operations are the key to solving the node.js chunk garbled problem. In addition, you can also optimize the performance of file transfer by adjusting the chunk size. If you need to process large files, you can consider using streams for chunked transfer. By correctly encoding and decoding chunk data, we can avoid the problem of garbled chunks and improve the reliability and efficiency of file transmission.

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