DefinitelyTyped/types/merge2/merge2-tests.ts

import * as gulp from 'gulp';
import merge2 = require('merge2');

gulp.task('app-js', () =>
  merge2(
      gulp.src('static/src/tpl/*.html'),
      gulp.src([
        'static/src/js/app.js',
        'static/src/js/locale_zh-cn.js',
        'static/src/js/router.js',
        'static/src/js/tools.js',
        'static/src/js/services.js',
        'static/src/js/filters.js',
        'static/src/js/directives.js',
        'static/src/js/controllers.js'
      ])
    )
    .pipe(gulp.dest('static/dist/js/'))
);

const stream1 = gulp.src('*.html');
const stream2 = gulp.src('*.html');
const stream3 = gulp.src('*.html');
const stream4 = gulp.src('*.html');
const stream5 = gulp.src('*.html');
const stream6 = gulp.src('*.html');
const stream7 = gulp.src('*.html');

let stream = merge2([stream1, stream2], stream3, {end: false});

stream.once('queueDrain', () => {
    stream.add(stream4, stream5);
});

// ..
stream.end();

// equal to merge2([stream1, stream2], stream3)
stream = merge2();
stream.add([stream1, stream2]);
stream.add(stream3);

stream.on('data', (data: any) => {
  console.log(data);
});

// merge order:
//   1. merge `stream1`;
//   2. merge `stream2` and `stream3` in parallel after `stream1` merged;
//   3. merge 'stream4' after `stream2` and `stream3` merged;
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]);
stream = merge2(streamA, streamB);
streamA.add(stream6);

stream.on('readable', () => {
    console.log('Stream has data!!');
});