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var batchThese = require("batch-these")

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batch-these v0.8.0

batch with ease


build NPM version

batch data with ease


npm install --save batch-these


var batch = require('batch-these');
    batch.wait(10); // 10 miliseconds tops

process.on('stuff-started', function(e){
  var chunk =;
  batch.these(chunk, function(data){
    console.log('Started ', data.join(', ') );

process.on('stuff-done', function(e){
  var chunk = + ' in ' + Math.floor(e.time) + ' ms';
  batch.these(chunk, function(data){
    console.log('Done with Mr.', data.join(', Mr. ') );

var dogs = ['Blue', 'Pink', 'Eddie', 'Joe','White','Brown', 'Blonde','Orange'];

dogs.forEach(function(name, index){
  var time = process.hrtime();
    process.emit('stuff-started', {
      name : name,
      time : time

    var rand = Math.floor(Math.random()*100);
      process.emit('stuff-done', {
        name : name,
        time : process.hrtime(time)[1]/1000000
    }, rand);
  }, (index + 1)*11);

which will output something similar to

Started  Blue, Pink, Eddie, Joe, White
Done with Mr. Pink in 31 ms
Started  Brown
Done with Mr. Joe in 20 ms, Mr. Brown in 3 ms, Mr. Eddie in 37 ms, Mr. Blue in 59 ms
Started  Blonde
Done with Mr. White in 20 ms
Started  Orange
Done with Mr. Blonde in 15 ms
Done with Mr. Orange in 44 ms


var batch = require('batch-these')

batch.these(chunk, callback)

chunk type: none | default: none

Data to be accumulated.

function to pass the data when the time comes.[callback])

How to store your chunks. This is the default

function batchStore(batch, chunk){ = || [ ];;
}; returns the current storer.


Decides how the chunks are accumulated. The default is

function batchFilter(batch, caller){
  return batch.location === caller.location;

Where location has the stack format filename:lineNumber:columNumber

batch.filter() returns the current filter.



type: number | default: 0 miliseconds

Time in ms to wait in between batches.



type: function | default: console.log

Function to track down for the batches.

how it works

Internally is using callers-module to get only 1 stacktrace frame. With that frame one can figure out the exact location of the callback. Based on that, a batch is stored. For each location a batch will kept waiting for a new chunk using a timer. Thats it.

The time to be waiting is set with batch.wait([ms]) time.

The origin from which the stacktrace will be taken is set with batch.origin([handle])

NOTE: the package is devised to work hand in hand with process.stdout.write. That is, the package monkeypatches stdout in order to feed from its data.

Though it would need some changes as it is, it should work with any other function call. With a prior patch, that is.


You would like to keep stdout writes to the bare minimum.


npm test



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