Memory Streams JS is a light-weight implementation of the Stream.Readable and Stream.Writable abstract classes from node.js. You can use the classes provided to store the result of reading and writing streams in memory. This can be useful when you need pipe your test output for later inspection or to stream files from the web into memory without have to use temporary files on disk.

Install with:

npm install memory-streams --save

Sample usage, using the ReadableStream class and piping:

var streams = require('memory-streams');

// Initialize with the string
var reader = new streams.ReadableStream('Hello World\n');

// Send all output to stdout
reader.pipe(process.stdout); // outputs: "Hello World\n"

// Add more data to the stream
reader.append('Hello Universe\n'); // outputs "Hello Universe\n";

Using the ReadableStream class and reading manually:

var streams = require('memory-streams');

// Initialize with the string
var reader = new streams.ReadableStream('Hello World\n');

// Add more data to the stream
reader.append('Hello Universe\n'); // outputs "Hello Universe\n";

// Read the data out
console.log(reader.read().toString()); // outputs: "Hello World\nHello Universe\n"

Using the WritableStream class and piping the contents of a file:

var streams = require('memory-streams')
  , fs      = require('fs');

// Pipe 
var reader = fs.createReadStream('index.js');
var writer = new streams.WritableStream();
reader.pipe(writer);
reader.on('readable', function() {

  // Output the content as a string
  console.log(writer.toString());
  
  // Output the content as a Buffer
  console.log(writer.toBuffer());
});

You can also call the write method directly to store data to the stream:

var streams = require('memory-streams');

// Write method
var writer = new streams.WritableStream();
writer.write('Hello World\n');

// Output the content as a string
console.log(writer.toString()); // Outputs: "Hello World\n"

For more examples you can look at the tests for the module.

MIT

Copyright (c) 2017 Paul Jackson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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