我通常使用这个简单的函数将流转换为字符串:

function streamToString(stream, cb) {
  const chunks = [];
  stream.on('data', (chunk) => {
    chunks.push(chunk.toString());
  });
  stream.on('end', () => {
    cb(chunks.join(''));
  });
}

使用的例子:

let stream = fs.createReadStream('./myFile.foo');
streamToString(stream, (data) => {
  console.log(data);  // data is now my string variable
});

像减流器这样的东西怎么样?

下面是一个使用ES6类的例子如何使用一个。

var stream = require('stream')

class StreamReducer extends stream.Writable {
  constructor(chunkReducer, initialvalue, cb) {
    super();
    this.reducer = chunkReducer;
    this.accumulator = initialvalue;
    this.cb = cb;
  }
  _write(chunk, enc, next) {
    this.accumulator = this.reducer(this.accumulator, chunk);
    next();
  }
  end() {
    this.cb(null, this.accumulator)
  }
}

// just a test stream
class EmitterStream extends stream.Readable {
  constructor(chunks) {
    super();
    this.chunks = chunks;
  }
  _read() {
    this.chunks.forEach(function (chunk) { 
        this.push(chunk);
    }.bind(this));
    this.push(null);
  }
}

// just transform the strings into buffer as we would get from fs stream or http request stream
(new EmitterStream(
  ["hello ", "world !"]
  .map(function(str) {
     return Buffer.from(str, 'utf8');
  })
)).pipe(new StreamReducer(
  function (acc, v) {
    acc.push(v);
    return acc;
  },
  [],
  function(err, chunks) {
    console.log(Buffer.concat(chunks).toString('utf8'));
  })
);

这对我来说是有效的，并且基于Node v6.7.0文档:

let output = '';
stream.on('readable', function() {
    let read = stream.read();
    if (read !== null) {
        // New stream data is available
        output += read.toString();
    } else {
        // Stream is now finished when read is null.
        // You can callback here e.g.:
        callback(null, output);
    }
});

stream.on('error', function(err) {
  callback(err, null);
})

我通常使用这个简单的函数将流转换为字符串:

function streamToString(stream, cb) {
  const chunks = [];
  stream.on('data', (chunk) => {
    chunks.push(chunk.toString());
  });
  stream.on('end', () => {
    cb(chunks.join(''));
  });
}

使用的例子:

let stream = fs.createReadStream('./myFile.foo');
streamToString(stream, (data) => {
  console.log(data);  // data is now my string variable
});

另一种方法是将流转换为promise(参考下面的示例)，然后使用then(或await)将解析值分配给变量。

function streamToString (stream) {
  const chunks = [];
  return new Promise((resolve, reject) => {
    stream.on('data', (chunk) => chunks.push(Buffer.from(chunk)));
    stream.on('error', (err) => reject(err));
    stream.on('end', () => resolve(Buffer.concat(chunks).toString('utf8')));
  })
}

const result = await streamToString(stream)

所有列出的答案似乎都以流动模式打开可读流，这不是NodeJS的默认模式，并且可能有局限性，因为它缺乏NodeJS在暂停可读流模式中提供的反压力支持。 这里是一个使用Just Buffers、本机流和本机流转换并支持对象模式的实现

import {Transform} from 'stream';

let buffer =null;    

function objectifyStream() {
    return new Transform({
        objectMode: true,
        transform: function(chunk, encoding, next) {

            if (!buffer) {
                buffer = Buffer.from([...chunk]);
            } else {
                buffer = Buffer.from([...buffer, ...chunk]);
            }
            next(null, buffer);
        }
    });
}

process.stdin.pipe(objectifyStream()).process.stdout