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var merge2 = require("merge2")

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merge2 v1.4.1

Merge multiple streams into one stream in sequence or parallel.


Merge multiple streams into one stream in sequence or parallel.

NPM version Build Status Downloads


Install with npm

npm install merge2


const gulp = require('gulp')
const merge2 = require('merge2')
const concat = require('gulp-concat')
const minifyHtml = require('gulp-minify-html')
const ngtemplate = require('gulp-ngtemplate')

gulp.task('app-js', function () {
  return merge2(
        .pipe(minifyHtml({empty: true}))
          module: 'genTemplates',
          standalone: true
      ), gulp.src([
const stream = merge2([stream1, stream2], stream3, {end: false})
stream.add(stream4, stream5)
// equal to merge2([stream1, stream2], stream3)
const stream = merge2()
stream.add([stream1, stream2])
// merge order:
//   1. merge `stream1`;
//   2. merge `stream2` and `stream3` in parallel after `stream1` merged;
//   3. merge 'stream4' after `stream2` and `stream3` merged;
const stream = merge2(stream1, [stream2, stream3], stream4)

// merge order:
//   1. merge `stream5` and `stream6` in parallel after `stream4` merged;
//   2. merge 'stream7' after `stream5` and `stream6` merged;
stream.add([stream5, stream6], stream7)
// nest merge
// equal to merge2(stream1, stream2, stream6, stream3, [stream4, stream5]);
const streamA = merge2(stream1, stream2)
const streamB = merge2(stream3, [stream4, stream5])
const stream = merge2(streamA, streamB)


const merge2 = require('merge2')



merge2(stream1, stream2, ..., streamN)

merge2(stream1, stream2, ..., streamN, options)

merge2(stream1, [stream2, stream3, ...], streamN, options)

return a duplex stream (mergedStream). streams in array will be merged in parallel.


mergedStream.add(stream1, [stream2, stream3, ...], ...)

return the mergedStream.

mergedStream.on('queueDrain', function() {})

It will emit 'queueDrain' when all streams merged. If you set end === false in options, this event give you a notice that should add more streams to merge or end the mergedStream.


option Type: Readable or Duplex or Transform stream.


option Type: Object.

  • end - Boolean - if end === false then mergedStream will not be auto ended, you should end by yourself. Default: undefined

  • pipeError - Boolean - if pipeError === true then mergedStream will emit error event from source streams. Default: undefined

  • objectMode - Boolean . Default: true

objectMode and other options(highWaterMark, defaultEncoding ...) is same as Node.js Stream.


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