如何在 NodeJS 中创建空的（立即完成的）ReadWriteStream？

发布于 2025-01-14 14:33:33 字数 878 浏览 4 评论 0原文

如何创建空的 NodeJS.ReadWriteStream 它将立即停止？

如果您感兴趣为什么我需要这样做，我正在开发该功能对于 Gulp，它基本上通过 Gulp.src()< 返回 NodeJS.ReadWriteStream /代码>。但在某些条件下，任务一定不能执行。伪代码是

function provideStylesProcessing(
  config: { /* various settings */ }
): () => NodeJS.ReadWriteStream {
    
    if (/* certain conditions */) {
      Return immideately ended NodeJS.ReadWriteStream
    }


    // Else use Gulp functionality as usual
    return (): NodeJS.ReadWriteStream => Gulp.src(entryPointsSourceFilesAbsolutePaths).
          pipe(/* ... */);
}

您可能会推荐“您可以返回空的 Promise”。是的，这是一个替代方案，但我不想使功能复杂化：如果任务是基于steam的，它应该返回溪流;如果基于回调 - 回调（它包装到函数以允许添加参数）等等。

原文

How to create empty NodeJS.ReadWriteStream which will immideately stopped?

If you are interesting why I need to do this, I am developing the function
for Gulp, which basically returns NodeJS.ReadWriteStream via Gulp.src().
But under certain conditions, the task must not be executed. The pseudo code is

function provideStylesProcessing(
  config: { /* various settings */ }
): () => NodeJS.ReadWriteStream {
    
    if (/* certain conditions */) {
      Return immideately ended NodeJS.ReadWriteStream
    }


    // Else use Gulp functionality as usual
    return (): NodeJS.ReadWriteStream => Gulp.src(entryPointsSourceFilesAbsolutePaths).
          pipe(/* ... */);
}

You may reccomend "you can return the empty Promise instead". Yes, this is an alternative,
but I don't want to complicate the function: if task is steam based, it should return the
stream; if callback based - callback (it wrapped to function to allows the adding of parameters) and so on.

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兲鉂ぱ嘚淚 2025-01-21 14:33:33

您可以使用任何空的双工流，例如虚拟 PassThrough 流，并使用 .end() 手动结束它。

const { PassThrough } = require('stream');

function provideStylesProcessing(
  config: { /* various settings */ }
): () => NodeJS.ReadWriteStream {
    
    if (/* certain conditions */) {
      return () => new PassThrough().end();
    }

    ...
}

You can use any empty duplex stream, for example a dummy PassThrough stream, and end it manually with .end().

const { PassThrough } = require('stream');

function provideStylesProcessing(
  config: { /* various settings */ }
): () => NodeJS.ReadWriteStream {
    
    if (/* certain conditions */) {
      return () => new PassThrough().end();
    }

    ...
}

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天荒地未老 2025-01-21 14:33:33

您可以使用 PassThrough 流来执行此操作：

PassThrough 流是一种 Transform 流，它仅传递数据而不对其进行转换。

import { PassThrough } from 'stream';

const xs = new PassThrough({
  objectMode: true
});

xs.end();

xs.on('finish', () => {
  console.log('This stream has ended');
});

You can use a PassThrough stream to do this:

A PassThrough stream is a Transform stream that just passes the data through without transforming it.

import { PassThrough } from 'stream';

const xs = new PassThrough({
  objectMode: true
});

xs.end();

xs.on('finish', () => {
  console.log('This stream has ended');
});

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