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// indexedDB doc: https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_API/Using_IndexedDB#basic_pattern
const pdb = new Promise((resolve, reject) => {

  const request = indexedDB.open("compiledCache", 1);

  request.onerror = (event) => reject(event);
  request.onsuccess = (event) => resolve(event.target.result);
  request.onupgradeneeded = (event) => {

    request.onsuccess = null;

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import { Duplex } from 'stream'

export default class Duplexify extends Duplex {

	constructor(writable, readable) {

		super({
			readableObjectMode: readable.readableObjectMode,
			writableObjectMode: writable.writableObjectMode,
			readableHighWaterMark: readable.readableHighWaterMark,

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// javascript jpeg decoder: https://github.com/eugeneware/jpeg-js/blob/79c4c7ea876d2e7b46981a563fcc4ae8f9e19849/lib/decoder.js
// Determine the JPEG compression quality from the quantization tables: https://github.com/ImageMagick/ImageMagick/blob/59f28acff016f6ae5e8b7e6300bcdf97e94affc9/coders/jpeg.c#L879
// JPEG File Layout and Format: http://vip.sugovica.hu/Sardi/kepnezo/JPEG%20File%20Layout%20and%20Format.htm
// jpeg constants: https://github.com/LuaDist/libjpeg/blob/6c0fcb8ddee365e7abc4d332662b06900612e923/jpeglib.h#L45

function getQuantizationTables(data) {

	var quantizationTables = []

	var dctZigZag = new Int32Array([