merge-stream
Advanced tools
Package description
The merge-stream npm package is used to create a stream that emits events from multiple other streams. This is useful when you want to handle multiple streams as if they were a single stream, for example, when you are dealing with multiple sources of data or tasks in a build process.
Merging multiple streams
This feature allows you to merge multiple streams into one. In the code sample, `stream1` and `stream2` are merged into `mergedStream`. You can then listen to events from `mergedStream` as if it was a single stream.
var stream1 = source1.pipe(transform1);
var stream2 = source2.pipe(transform2);
var mergedStream = mergeStream(stream1, stream2);
mergedStream.on('data', function(data) {
console.log(data);
});Adding streams dynamically
This feature allows you to add streams to the merged stream dynamically. Initially, `mergedStream` is created without any sources. Streams `stream1` and `stream2` are then created and added to `mergedStream` dynamically.
var mergedStream = mergeStream();
var stream1 = source1.pipe(transform1);
mergedStream.add(stream1);
var stream2 = source2.pipe(transform2);
mergedStream.add(stream2);Similar to merge-stream, multistream allows you to combine multiple streams into one. However, multistream works by taking an array of streams or a function that returns a stream, and reads them one after the other, not necessarily in parallel as merge-stream does.
Combined-stream is another package that is similar to merge-stream. It is used to create a stream that emits data from multiple streams one after the other. It differs from merge-stream in that it does not handle the streams in parallel but sequentially.
Pumpify combines streams into a single duplex stream. This is similar to merge-stream in that it deals with multiple streams, but pumpify is more about creating a pipeline of streams where the output of one stream is the input to the next, rather than merging their outputs.
Readme
Merge (interleave) a bunch of streams.
var stream1 = new Stream();
var stream2 = new Stream();
var merged = mergeStream(stream1, stream2);
var stream3 = new Stream();
merged.add(stream3);
merged.isEmpty();
//=> false
This is adapted from event-stream separated into a new module, using Streams3.
mergeStreamType: function
Merges an arbitrary number of streams. Returns a merged stream.
merged.addA method to dynamically add more sources to the stream. The argument supplied to add can be either a source or an array of sources.
merged.isEmptyA method that tells you if the merged stream is empty.
When a stream is "empty" (aka. no sources were added), it could not be returned to a gulp task.
So, we could do something like this:
stream = require('merge-stream')();
// Something like a loop to add some streams to the merge stream
// stream.add(streamA);
// stream.add(streamB);
return stream.isEmpty() ? null : stream;
An example use case for merge-stream is to combine parts of a task in a project's gulpfile.js like this:
const gulp = require('gulp');
const htmlValidator = require('gulp-w3c-html-validator');
const jsHint = require('gulp-jshint');
const mergeStream = require('merge-stream');
function lint() {
return mergeStream(
gulp.src('src/*.html')
.pipe(htmlValidator())
.pipe(htmlValidator.reporter()),
gulp.src('src/*.js')
.pipe(jsHint())
.pipe(jsHint.reporter())
);
}
gulp.task('lint', lint);
MIT
FAQs
Create a stream that emits events from multiple other streams
The npm package merge-stream receives a total of 33,084,822 weekly downloads. As such, merge-stream popularity was classified as popular.
We found that merge-stream demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
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