Nocturnal Prancing Mosquito

    batch-iterator

    1.5.0 • Public • Published

    batch-iterator

    JavaScript batch iterator using promises.

    Useful when you need to throttle how many concurrent processes are running simultaneously, while being notified when they're all done (or something fails).

    Installation

    npm install batch-iterator --save
    

    Usage

    var iterator = require('batch-iterator');
    
    iterator(list, batchSize, promise, data)
      .then(function(accumulator) {
        console.log('List of result from promise', accumulator);
      })
      .catch(function(err) {
        console.log("A promise failed", err);
      });
    

    The list will be iterated, and each item in the list will be passed on to the promise callback.

    batchSize is how many items in the list should be started simultaneously. Default size is 10. If set to 0, all array elements are processed at once. If negative values are provided, 'Invalid batchSize' error is returned

    The accumulator is a list of the data resolved in each promise.

    The data will be passed to each function as additional data.

    The index of the array item is accessible as the LAST parameter of the passed function. (also afte 'data', if present)

    Example

    In the example below we use the Pageres module to capture 100 screenshots in batches of 10.

    const Pageres = require('pageres');
    const iterator = require('batch-iterator');
    const urls = ["https://github.io", ..., ]; // imagine 100 urls
    
    const startTime = Date.now();
    
    iterator(urls, 10, function(url) {
           var pageres = new Pageres();
           // Return the pageres promise
           return pageres
               .src(url, ['1024x768'])
               .dest(process.cwd() + '/screenshots')
               .run();
       })
       .then(function() {
         const endTime = Date.now();
         const diffTime = (endTime - startTime) / 1000;
         console.log("Screenshots captured in " + diffTime + " seconds.");
       })
       .catch(function(err) {
         console.log(err);
       });
    

    Install

    npm i batch-iterator

    DownloadsWeekly Downloads

    311

    Version

    1.5.0

    License

    MIT

    Unpacked Size

    9.2 kB

    Total Files

    5

    Last publish

    Collaborators

    • jofan