Utility function for spitting an array into chunks.

chunkArray.js

// Helpful if you're working with a very large array, that you need to send to a web server for processing.
// For example, after chunking the array, you can send a number of request to a web server in in parallel,
// and handle the response after all the chunks have been processed (see example below).
function chunkArray(array, chunkLength) {
  const length = array.length;
  const chunks = [];
  let index = 0;

  while (index < length) {
    chunks.push(array.slice(index, (index += chunkLength)));
  }

  return chunks;
}

// --- Example ---
// unitIds is an array containing the numbers 1 through 1M.
// this represents a large dataset you want to process against some web server,
// that can't handle a set of data that large in a single api call
const unitIds = Array.from(Array(1000000), (d, i) => ++i);

// unitIds, in 100 item chunks, to not overload web service call
const unitIdsChunks = chunkArray(unitIds, 100);

// request data with each chunk of unitIds
const $deferreds = [];
unitIdsChunks.forEach(function(chunk) {
  const = `https://www.example-web-service.com?data=${chunk.join(',')}`
  $deferreds.push($.get(url));
});

$.when($deferreds)
  .done(function(requests) {
    // chunkedData will hold the results of each web service request
    const chunkedData = [];
    requests.forEach(function(request) {
      request.done(function(data, textStatus, jqXHR) {
        chunkedData.push(data);
        // after the last request has been resolved
        if (chunkedData.length === requests.length) {
          console.log(chunkedData); // <----- handle chunked data!
        }
      });
    });
  })
  .fail(function() {
    console.error('Error with web service');
  });