Getting started with Uploading Large Files...

Step3-LargeFile-Preperation.js

import utils from './utils';

if (!ArrayBuffer.prototype.slice) {
  ArrayBuffer.prototype.slice = function (begin, end) {
    let len = this.byteLength;
    begin = (begin|0) || 0;
    end = end === (void 0) ? len : (end|0);

    // Handle negative values.
    if (begin < 0) begin = Math.max(begin + len, 0);
    if (end < 0) end = Math.max(end + len, 0);

    if (len === 0 || begin >= len || begin >= end) {
      return new ArrayBuffer(0);
    }

    let length = Math.min(len - begin, end - begin);
    let target = new ArrayBuffer(length);
    let targetArray = new Uint8Array(target);

    targetArray.set(new Uint8Array(this, begin, length));

    return target;
  };
}