# modules/html.js

    /* global jsPDF html2canvas */
    /**
     * Copyright (c) 2018 Erik Koopmans
     * Released under the MIT License.
     *
     * Licensed under the MIT License.
     * http://opensource.org/licenses/mit-license
     */

    /**
     * jsPDF html PlugIn
     *
     * @name html
     * @module
     */
    (function (jsPDFAPI, global) {
      'use strict';

      if (typeof Promise === 'undefined') {
        // eslint-disable-next-line no-console
        console.warn('Promise not found. html-Plugin will not work');
        return;
      }
      /**
      * Determine the type of a variable/object.
      *
      * @private
      * @ignore
      */
      var objType = function (obj) {
        var type = typeof obj;
        if (type === 'undefined') return 'undefined';
        else if (type === 'string' || obj instanceof String) return 'string';
        else if (type === 'number' || obj instanceof Number) return 'number';
        else if (type === 'function' || obj instanceof Function) return 'function';
        else if (!!obj && obj.constructor === Array) return 'array';
        else if (obj && obj.nodeType === 1) return 'element';
        else if (type === 'object') return 'object';
        else return 'unknown';
      };

      /**
      * Create an HTML element with optional className, innerHTML, and style.
      *
      * @private
      * @ignore
      */
      var createElement = function (tagName, opt) {
        var el = document.createElement(tagName);
        if (opt.className) el.className = opt.className;
        if (opt.innerHTML) {
          el.innerHTML = opt.innerHTML;
          var scripts = el.getElementsByTagName('script');
          for (var i = scripts.length; i-- > 0;) {
            scripts[i].parentNode.removeChild(scripts[i]);
          }
        }
        for (var key in opt.style) {
          el.style[key] = opt.style[key];
        }
        return el;
      };

      /**
      * Deep-clone a node and preserve contents/properties.
      *
      * @private
      * @ignore
      */
      var cloneNode = function (node, javascriptEnabled) {
        // Recursively clone the node.
        var clone = node.nodeType === 3 ? document.createTextNode(node.nodeValue) : node.cloneNode(false);
        for (var child = node.firstChild; child; child = child.nextSibling) {
          if (javascriptEnabled === true || child.nodeType !== 1 || child.nodeName !== 'SCRIPT') {
            clone.appendChild(cloneNode(child, javascriptEnabled));
          }
        }

        if (node.nodeType === 1) {
          // Preserve contents/properties of special nodes.
          if (node.nodeName === 'CANVAS') {
            clone.width = node.width;
            clone.height = node.height;
            clone.getContext('2d').drawImage(node, 0, 0);
          } else if (node.nodeName === 'TEXTAREA' || node.nodeName === 'SELECT') {
            clone.value = node.value;
          }

          // Preserve the node's scroll position when it loads.
          clone.addEventListener('load', function () {
            clone.scrollTop = node.scrollTop;
            clone.scrollLeft = node.scrollLeft;
          }, true);
        }

        // Return the cloned node.
        return clone;
      };

      /* ----- CONSTRUCTOR ----- */

      var Worker = function Worker(opt) {
        // Create the root parent for the proto chain, and the starting Worker.
        var root = Object.assign(Worker.convert(Promise.resolve()),
          JSON.parse(JSON.stringify(Worker.template)));
        var self = Worker.convert(Promise.resolve(), root);

        // Set progress, optional settings, and return.
        self = self.setProgress(1, Worker, 1, [Worker]);
        self = self.set(opt);
        return self;
      };

      // Boilerplate for subclassing Promise.
      Worker.prototype = Object.create(Promise.prototype);
      Worker.prototype.constructor = Worker;

      // Converts/casts promises into Workers.
      Worker.convert = function convert(promise, inherit) {
        // Uses prototypal inheritance to receive changes made to ancestors' properties.
        promise.__proto__ = inherit || Worker.prototype;
        return promise;
      };

      Worker.template = {
        prop: {
          src: null,
          container: null,
          overlay: null,
          canvas: null,
          img: null,
          pdf: null,
          pageSize: null,
          callback: function () { }
        },
        progress: {
          val: 0,
          state: null,
          n: 0,
          stack: []
        },
        opt: {
          filename: 'file.pdf',
          margin: [0, 0, 0, 0],
          enableLinks: true,
          x: 0,
          y: 0,
          html2canvas: {},
          jsPDF: {}
        }
      };

      /* ----- FROM / TO ----- */

      Worker.prototype.from = function from(src, type) {
        function getType(src) {
          switch (objType(src)) {
            case 'string': return 'string';
            case 'element': return src.nodeName.toLowerCase === 'canvas' ? 'canvas' : 'element';
            default: return 'unknown';
          }
        }

        return this.then(function from_main() {
          type = type || getType(src);
          switch (type) {
            case 'string': return this.set({ src: createElement('div', { innerHTML: src }) });
            case 'element': return this.set({ src: src });
            case 'canvas': return this.set({ canvas: src });
            case 'img': return this.set({ img: src });
            default: return this.error('Unknown source type.');
          }
        });
      };

      Worker.prototype.to = function to(target) {
        // Route the 'to' request to the appropriate method.
        switch (target) {
          case 'container':
            return this.toContainer();
          case 'canvas':
            return this.toCanvas();
          case 'img':
            return this.toImg();
          case 'pdf':
            return this.toPdf();
          default:
            return this.error('Invalid target.');
        }
      };

      Worker.prototype.toContainer = function toContainer() {
        // Set up function prerequisites.
        var prereqs = [function checkSrc() {
          return this.prop.src || this.error('Cannot duplicate - no source HTML.');
        }, function checkPageSize() {
          return this.prop.pageSize || this.setPageSize();
        }];
        return this.thenList(prereqs).then(function toContainer_main() {
          // Define the CSS styles for the container and its overlay parent.
          var overlayCSS = {
            position: 'fixed',
            overflow: 'hidden',
            zIndex: 1000,
            left: '-100000px',
            right: 0,
            bottom: 0,
            top: 0
          };
          var containerCSS = {
            position: 'relative',
            display: 'inline-block',
            width: Math.max(this.prop.src.clientWidth, this.prop.src.scrollWidth, this.prop.src.offsetWidth) + 'px',
            left: 0,
            right: 0,
            top: 0,
            margin: 'auto',
            backgroundColor: 'white'
          }; // Set the overlay to hidden (could be changed in the future to provide a print preview).

          var source = cloneNode(this.prop.src, this.opt.html2canvas.javascriptEnabled);

          if (source.tagName === 'BODY') {
            containerCSS.height = Math.max(document.body.scrollHeight, document.body.offsetHeight, document.documentElement.clientHeight, document.documentElement.scrollHeight, document.documentElement.offsetHeight) + 'px';
          }

          this.prop.overlay = createElement('div', {
            className: 'html2pdf__overlay',
            style: overlayCSS
          });
          this.prop.container = createElement('div', {
            className: 'html2pdf__container',
            style: containerCSS
          });
          this.prop.container.appendChild(source);
          this.prop.container.firstChild.appendChild(createElement('div', {
            style: {
              clear: 'both',
              border: '0 none transparent',
              margin: 0,
              padding: 0,
              height: 0
            }
          }));
          this.prop.container.style.float = 'none';
          this.prop.overlay.appendChild(this.prop.container);
          document.body.appendChild(this.prop.overlay);
          this.prop.container.firstChild.style.position = 'relative';
          this.prop.container.height = Math.max(this.prop.container.firstChild.clientHeight, this.prop.container.firstChild.scrollHeight, this.prop.container.firstChild.offsetHeight) + 'px';
        });
      };

      Worker.prototype.toCanvas = function toCanvas() {
        // Set up function prerequisites.
        var prereqs = [
          function checkContainer() {
            return document.body.contains(this.prop.container)
              || this.toContainer();
          }
        ];

        // Fulfill prereqs then create the canvas.
        return this.thenList(prereqs).then(function toCanvas_main() {
          // Handle old-fashioned 'onrendered' argument.
          var options = Object.assign({}, this.opt.html2canvas);
          delete options.onrendered;

          if (!this.isHtml2CanvasLoaded()) {
            return;
          }
          return html2canvas(this.prop.container, options);
        }).then(function toCanvas_post(canvas) {
          // Handle old-fashioned 'onrendered' argument.
          var onRendered = this.opt.html2canvas.onrendered || function () { };
          onRendered(canvas);

          this.prop.canvas = canvas;
          document.body.removeChild(this.prop.overlay);
        });
      };

      Worker.prototype.toContext2d = function toContext2d() {
        // Set up function prerequisites.
        var prereqs = [
          function checkContainer() {
            return document.body.contains(this.prop.container)
              || this.toContainer();
          }
        ];

        // Fulfill prereqs then create the canvas.
        return this.thenList(prereqs).then(function toContext2d_main() {
          // Handle old-fashioned 'onrendered' argument.

          var pdf = this.opt.jsPDF;
          var options = Object.assign({
            async: true,
            allowTaint: true,
            backgroundColor: '#ffffff',
            imageTimeout: 15000,
            logging: true,
            proxy: null,
            removeContainer: true,
            foreignObjectRendering: false,
            useCORS: false
          }, this.opt.html2canvas);
          delete options.onrendered;

          pdf.context2d.autoPaging = true;
          pdf.context2d.posX = this.opt.x;
          pdf.context2d.posY = this.opt.y;

          options.windowHeight = options.windowHeight || 0;
          options.windowHeight = (options.windowHeight == 0) ? Math.max(this.prop.container.clientHeight, this.prop.container.scrollHeight, this.prop.container.offsetHeight) : options.windowHeight;

          if (!this.isHtml2CanvasLoaded()) {
            return;
          }

          return html2canvas(this.prop.container, options);
        }).then(function toContext2d_post(canvas) {
          // Handle old-fashioned 'onrendered' argument.
          var onRendered = this.opt.html2canvas.onrendered || function () { };
          onRendered(canvas);

          this.prop.canvas = canvas;
          document.body.removeChild(this.prop.overlay);
        });
      };

      Worker.prototype.toImg = function toImg() {
        // Set up function prerequisites.
        var prereqs = [
          function checkCanvas() { return this.prop.canvas || this.toCanvas(); }
        ];

        // Fulfill prereqs then create the image.
        return this.thenList(prereqs).then(function toImg_main() {
          var imgData = this.prop.canvas.toDataURL('image/' + this.opt.image.type, this.opt.image.quality);
          this.prop.img = document.createElement('img');
          this.prop.img.src = imgData;
        });
      };

      Worker.prototype.toPdf = function toPdf() {
        // Set up function prerequisites.
        var prereqs = [
          function checkContext2d() { return this.toContext2d(); }
          //function checkCanvas() { return this.prop.canvas || this.toCanvas(); }
        ];

        // Fulfill prereqs then create the image.
        return this.thenList(prereqs).then(function toPdf_main() {
          // Create local copies of frequently used properties.
          this.prop.pdf = this.prop.pdf || this.opt.jsPDF;
        });
      };

      /* ----- OUTPUT / SAVE ----- */

      Worker.prototype.output = function output(type, options, src) {
        // Redirect requests to the correct function (outputPdf / outputImg).
        src = src || 'pdf';
        if (src.toLowerCase() === 'img' || src.toLowerCase() === 'image') {
          return this.outputImg(type, options);
        } else {
          return this.outputPdf(type, options);
        }
      };

      Worker.prototype.outputPdf = function outputPdf(type, options) {
        // Set up function prerequisites.
        var prereqs = [
          function checkPdf() { return this.prop.pdf || this.toPdf(); }
        ];

        // Fulfill prereqs then perform the appropriate output.
        return this.thenList(prereqs).then(function outputPdf_main() {
          /* Currently implemented output types:
           *    https://rawgit.com/MrRio/jsPDF/master/docs/jspdf.js.html#line992
           *  save(options), arraybuffer, blob, bloburi/bloburl,
           *  datauristring/dataurlstring, dataurlnewwindow, datauri/dataurl
           */
          return this.prop.pdf.output(type, options);
        });
      };

      Worker.prototype.outputImg = function outputImg(type) {
        // Set up function prerequisites.
        var prereqs = [
          function checkImg() { return this.prop.img || this.toImg(); }
        ];

        // Fulfill prereqs then perform the appropriate output.
        return this.thenList(prereqs).then(function outputImg_main() {
          switch (type) {
            case undefined:
            case 'img':
              return this.prop.img;
            case 'datauristring':
            case 'dataurlstring':
              return this.prop.img.src;
            case 'datauri':
            case 'dataurl':
              return document.location.href = this.prop.img.src;
            default:
              throw 'Image output type "' + type + '" is not supported.';
          }
        });
      };

      Worker.prototype.isHtml2CanvasLoaded = function () {
        var result = typeof global.html2canvas !== "undefined";
        if (!result) {
          throw new Error("html2canvas not loaded.");
        }
        return result;
      };

      Worker.prototype.save = function save(filename) {
        // Set up function prerequisites.
        var prereqs = [
          function checkPdf() { return this.prop.pdf || this.toPdf(); }
        ];

        if (!this.isHtml2CanvasLoaded()) {
          return;
        }

        // Fulfill prereqs, update the filename (if provided), and save the PDF.
        return this.thenList(prereqs).set(
          filename ? { filename: filename } : null
        ).then(function save_main() {
          this.prop.pdf.save(this.opt.filename);
        });
      };

      Worker.prototype.doCallback = function doCallback() {
        // Set up function prerequisites.
        var prereqs = [
          function checkPdf() { return this.prop.pdf || this.toPdf(); }
        ];

        if (!this.isHtml2CanvasLoaded()) {
          return;
        }
        // Fulfill prereqs, update the filename (if provided), and save the PDF.
        return this.thenList(prereqs)
          .then(function doCallback_main() {
            this.prop.callback(this.prop.pdf);
          });
      };

      /* ----- SET / GET ----- */

      Worker.prototype.set = function set(opt) {
        // TODO: Implement ordered pairs?

        // Silently ignore invalid or empty input.
        if (objType(opt) !== 'object') {
          return this;
        }

        // Build an array of setter functions to queue.
        var fns = Object.keys(opt || {}).map(function (key) {
          if (key in Worker.template.prop) {
            // Set pre-defined properties.
            return function set_prop() { this.prop[key] = opt[key]; }
          } else {
            switch (key) {
              case 'margin':
                return this.setMargin.bind(this, opt.margin);
              case 'jsPDF':
                return function set_jsPDF() { this.opt.jsPDF = opt.jsPDF; return this.setPageSize(); }
              case 'pageSize':
                return this.setPageSize.bind(this, opt.pageSize);
              default:
                // Set any other properties in opt.
                return function set_opt() { this.opt[key] = opt[key] };
            }
          }
        }, this);

        // Set properties within the promise chain.
        return this.then(function set_main() {
          return this.thenList(fns);
        });
      };

      Worker.prototype.get = function get(key, cbk) {
        return this.then(function get_main() {
          // Fetch the requested property, either as a predefined prop or in opt.
          var val = (key in Worker.template.prop) ? this.prop[key] : this.opt[key];
          return cbk ? cbk(val) : val;
        });
      };

      Worker.prototype.setMargin = function setMargin(margin) {
        return this.then(function setMargin_main() {
          // Parse the margin property.
          switch (objType(margin)) {
            case 'number':
              margin = [margin, margin, margin, margin];
            // eslint-disable-next-line no-fallthrough
            case 'array':
              if (margin.length === 2) {
                margin = [margin[0], margin[1], margin[0], margin[1]];
              }
              if (margin.length === 4) {
                break;
              }
            // eslint-disable-next-line no-fallthrough
            default:
              return this.error('Invalid margin array.');
          }

          // Set the margin property, then update pageSize.
          this.opt.margin = margin;
        }).then(this.setPageSize);
      };

      Worker.prototype.setPageSize = function setPageSize(pageSize) {
        function toPx(val, k) {
          return Math.floor(val * k / 72 * 96);
        }

        return this.then(function setPageSize_main() {
          // Retrieve page-size based on jsPDF settings, if not explicitly provided.
          pageSize = pageSize || jsPDF.getPageSize(this.opt.jsPDF);

          // Add 'inner' field if not present.
          if (!pageSize.hasOwnProperty('inner')) {
            pageSize.inner = {
              width: pageSize.width - this.opt.margin[1] - this.opt.margin[3],
              height: pageSize.height - this.opt.margin[0] - this.opt.margin[2]
            };
            pageSize.inner.px = {
              width: toPx(pageSize.inner.width, pageSize.k),
              height: toPx(pageSize.inner.height, pageSize.k)
            };
            pageSize.inner.ratio = pageSize.inner.height / pageSize.inner.width;
          }

          // Attach pageSize to this.
          this.prop.pageSize = pageSize;
        });
      };

      Worker.prototype.setProgress = function setProgress(val, state, n, stack) {
        // Immediately update all progress values.
        if (val != null) this.progress.val = val;
        if (state != null) this.progress.state = state;
        if (n != null) this.progress.n = n;
        if (stack != null) this.progress.stack = stack;
        this.progress.ratio = this.progress.val / this.progress.state;

        // Return this for command chaining.
        return this;
      };

      Worker.prototype.updateProgress = function updateProgress(val, state, n, stack) {
        // Immediately update all progress values, using setProgress.
        return this.setProgress(
          val ? this.progress.val + val : null,
          state ? state : null,
          n ? this.progress.n + n : null,
          stack ? this.progress.stack.concat(stack) : null
        );
      };

      /* ----- PROMISE MAPPING ----- */

      Worker.prototype.then = function then(onFulfilled, onRejected) {
        // Wrap `this` for encapsulation.
        var self = this;

        return this.thenCore(onFulfilled, onRejected, function then_main(onFulfilled, onRejected) {
          // Update progress while queuing, calling, and resolving `then`.
          self.updateProgress(null, null, 1, [onFulfilled]);
          return Promise.prototype.then.call(this, function then_pre(val) {
            self.updateProgress(null, onFulfilled);
            return val;
          }).then(onFulfilled, onRejected).then(function then_post(val) {
            self.updateProgress(1);
            return val;
          });
        });
      };

      Worker.prototype.thenCore = function thenCore(onFulfilled, onRejected, thenBase) {
        // Handle optional thenBase parameter.
        thenBase = thenBase || Promise.prototype.then;

        // Wrap `this` for encapsulation and bind it to the promise handlers.
        var self = this;
        if (onFulfilled) { onFulfilled = onFulfilled.bind(self); }
        if (onRejected) { onRejected = onRejected.bind(self); }

        // Cast self into a Promise to avoid polyfills recursively defining `then`.
        var isNative = Promise.toString().indexOf('[native code]') !== -1 && Promise.name === 'Promise';
        var selfPromise = isNative ? self : Worker.convert(Object.assign({}, self), Promise.prototype);

        // Return the promise, after casting it into a Worker and preserving props.
        var returnVal = thenBase.call(selfPromise, onFulfilled, onRejected);
        return Worker.convert(returnVal, self.__proto__);
      };

      Worker.prototype.thenExternal = function thenExternal(onFulfilled, onRejected) {
        // Call `then` and return a standard promise (exits the Worker chain).
        return Promise.prototype.then.call(this, onFulfilled, onRejected);
      };

      Worker.prototype.thenList = function thenList(fns) {
        // Queue a series of promise 'factories' into the promise chain.
        var self = this;
        fns.forEach(function thenList_forEach(fn) {
          self = self.thenCore(fn);
        });
        return self;
      };

      Worker.prototype['catch'] = function (onRejected) {
        // Bind `this` to the promise handler, call `catch`, and return a Worker.
        if (onRejected) { onRejected = onRejected.bind(this); }
        var returnVal = Promise.prototype['catch'].call(this, onRejected);
        return Worker.convert(returnVal, this);
      };

      Worker.prototype.catchExternal = function catchExternal(onRejected) {
        // Call `catch` and return a standard promise (exits the Worker chain).
        return Promise.prototype['catch'].call(this, onRejected);
      };

      Worker.prototype.error = function error(msg) {
        // Throw the error in the Promise chain.
        return this.then(function error_main() {
          throw new Error(msg);
        });
      };

      /* ----- ALIASES ----- */

      Worker.prototype.using = Worker.prototype.set;
      Worker.prototype.saveAs = Worker.prototype.save;
      Worker.prototype.export = Worker.prototype.output;
      Worker.prototype.run = Worker.prototype.then;

      // Get dimensions of a PDF page, as determined by jsPDF.
      jsPDF.getPageSize = function (orientation, unit, format) {
        // Decode options object
        if (typeof orientation === 'object') {
          var options = orientation;
          orientation = options.orientation;
          unit = options.unit || unit;
          format = options.format || format;
        }

        // Default options
        unit = unit || 'mm';
        format = format || 'a4';
        orientation = ('' + (orientation || 'P')).toLowerCase();
        var format_as_string = ('' + format).toLowerCase();

        // Size in pt of various paper formats
        var pageFormats = {
          'a0': [2383.94, 3370.39], 'a1': [1683.78, 2383.94],
          'a2': [1190.55, 1683.78], 'a3': [841.89, 1190.55],
          'a4': [595.28, 841.89], 'a5': [419.53, 595.28],
          'a6': [297.64, 419.53], 'a7': [209.76, 297.64],
          'a8': [147.40, 209.76], 'a9': [104.88, 147.40],
          'a10': [73.70, 104.88], 'b0': [2834.65, 4008.19],
          'b1': [2004.09, 2834.65], 'b2': [1417.32, 2004.09],
          'b3': [1000.63, 1417.32], 'b4': [708.66, 1000.63],
          'b5': [498.90, 708.66], 'b6': [354.33, 498.90],
          'b7': [249.45, 354.33], 'b8': [175.75, 249.45],
          'b9': [124.72, 175.75], 'b10': [87.87, 124.72],
          'c0': [2599.37, 3676.54], 'c1': [1836.85, 2599.37],
          'c2': [1298.27, 1836.85], 'c3': [918.43, 1298.27],
          'c4': [649.13, 918.43], 'c5': [459.21, 649.13],
          'c6': [323.15, 459.21], 'c7': [229.61, 323.15],
          'c8': [161.57, 229.61], 'c9': [113.39, 161.57],
          'c10': [79.37, 113.39], 'dl': [311.81, 623.62],
          'letter': [612, 792],
          'government-letter': [576, 756],
          'legal': [612, 1008],
          'junior-legal': [576, 360],
          'ledger': [1224, 792],
          'tabloid': [792, 1224],
          'credit-card': [153, 243]
        };

        var k;
        // Unit conversion
        switch (unit) {
          case 'pt': k = 1; break;
          case 'mm': k = 72 / 25.4; break;
          case 'cm': k = 72 / 2.54; break;
          case 'in': k = 72; break;
          case 'px': k = 72 / 96; break;
          case 'pc': k = 12; break;
          case 'em': k = 12; break;
          case 'ex': k = 6; break;
          default:
            throw ('Invalid unit: ' + unit);
        }
        var pageHeight = 0;
        var pageWidth = 0;

        // Dimensions are stored as user units and converted to points on output
        if (pageFormats.hasOwnProperty(format_as_string)) {
          pageHeight = pageFormats[format_as_string][1] / k;
          pageWidth = pageFormats[format_as_string][0] / k;
        } else {
          try {
            pageHeight = format[1];
            pageWidth = format[0];
          } catch (err) {
            throw new Error('Invalid format: ' + format);
          }
        }

        var tmp;
        // Handle page orientation
        if (orientation === 'p' || orientation === 'portrait') {
          orientation = 'p';
          if (pageWidth > pageHeight) {
            tmp = pageWidth;
            pageWidth = pageHeight;
            pageHeight = tmp;
          }
        } else if (orientation === 'l' || orientation === 'landscape') {
          orientation = 'l';
          if (pageHeight > pageWidth) {
            tmp = pageWidth;
            pageWidth = pageHeight;
            pageHeight = tmp;
          }
        } else {
          throw ('Invalid orientation: ' + orientation);
        }

        // Return information (k is the unit conversion ratio from pts)
        var info = { 'width': pageWidth, 'height': pageHeight, 'unit': unit, 'k': k, 'orientation': orientation};
        return info;
      };

      /**
       * Generate a PDF from an HTML element or string using.
       *
       * @name html
       * @function
       * @param {HTMLElement|string} source The source HTMLElement or a string containing HTML.
       * @param {Object} [options] Collection of settings
       * @param {string} [options.callback] The mandatory callback-function gets as first parameter the current jsPDF instance
       *
       * @example
       * var doc = new jsPDF();
       *
       * doc.html(document.body, {
       *    callback: function (doc) {
       *      doc.save();
       *    }
       * });
       */
      jsPDFAPI.html = function (src, options) {
        'use strict';

        options = options || {};
        options.callback = options.callback || function () { };
        options.html2canvas = options.html2canvas || {};
        options.html2canvas.canvas = options.html2canvas.canvas || this.canvas;
        options.jsPDF = options.jsPDF || this;
        // Create a new worker with the given options.
        var worker = new Worker(options);

        if (!options.worker) {
          // If worker is not set to true, perform the traditional 'simple' operation.
          return worker.from(src).doCallback();
        } else {
          // Otherwise, return the worker for new Promise-based operation.
          return worker;
        }
      };
    })(jsPDF.API, (typeof window !== "undefined" && window || typeof global !== "undefined" && global));