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在压缩流上调用 .flush() 将使 zlib 返回尽可能多的当前输出。 这可能以降低压缩质量为代价，但在需要尽快提供数据时非常有用。

在以下示例中，flush() 用于将压缩的部分 HTTP 响应写入客户端：

const zlib = require('node:zlib');
const http = require('node:http');
const { pipeline } = require('node:stream');

http.createServer((request, response) => {
  // 为了简单起见，省略了接受编码检查。
  response.writeHead(200, { 'content-encoding': 'gzip' });
  const output = zlib.createGzip();
  let i;

  pipeline(output, response, (err) => {
    if (err) {
      // 如果发生错误，则无能为力，
      // 因为服务器已经发送了 200 响应代码，
      // 并且已经向客户端发送了一些数据。
      // 能做的最好的事情
      // 就是立即终止响应并记录错误。
      clearInterval(i);
      response.end();
      console.error('An error occurred:', err);
    }
  });

  i = setInterval(() => {
    output.write(`The current time is ${Date()}\n`, () => {
      // 数据已传给 zlib，
      // 但压缩算法可能已决定缓冲数据以进行更有效的压缩。
      // 一旦客户端准备好接收数据，
      // 调用 .flush() 将使数据可用。
      output.flush();
    });
  }, 1000);
}).listen(1337);

Calling .flush() on a compression stream will make zlib return as much output as currently possible. This may come at the cost of degraded compression quality, but can be useful when data needs to be available as soon as possible.

In the following example, flush() is used to write a compressed partial HTTP response to the client:

const zlib = require('node:zlib');
const http = require('node:http');
const { pipeline } = require('node:stream');

http.createServer((request, response) => {
  // For the sake of simplicity, the Accept-Encoding checks are omitted.
  response.writeHead(200, { 'content-encoding': 'gzip' });
  const output = zlib.createGzip();
  let i;

  pipeline(output, response, (err) => {
    if (err) {
      // If an error occurs, there's not much we can do because
      // the server has already sent the 200 response code and
      // some amount of data has already been sent to the client.
      // The best we can do is terminate the response immediately
      // and log the error.
      clearInterval(i);
      response.end();
      console.error('An error occurred:', err);
    }
  });

  i = setInterval(() => {
    output.write(`The current time is ${Date()}\n`, () => {
      // The data has been passed to zlib, but the compression algorithm may
      // have decided to buffer the data for more efficient compression.
      // Calling .flush() will make the data available as soon as the client
      // is ready to receive it.
      output.flush();
    });
  }, 1000);
}).listen(1337);