Read file chunks

gistfile1.js

// set chunk size
var chunkSize = 1024 * 1024 * 2; // 2Mb

// file from input
var readChunks = function(file) {

    var parts = [];
    var start = 0;
    var stop = chunkSize - 1;
    var chunksLength = Math.ceil(file.size / chunkSize);

    for (var i = 0; i < chunksLength; i++) {

      if (stop > file.size) {
        stop = file.size;
      }

      parts[i] = {start: start, stop: stop};

      start = stop + 1;
      stop = stop + chunkSize;
    }

    return parts;

  };