ES6-ify the code in `web/ui_utils.js`

These changes consists mainly of replacing `var` with `let`/`const`, adding a couple of default parameters to function signatures, and finally converting `EventBus`/`ProgressBar` to proper classes.

web/app.js

@@ -507,7 +507,7 @@ var PDFViewerApplication = {
   },
 
   get loadingBar() {
-    var bar = new ProgressBar('#loadingBar', {});
+    var bar = new ProgressBar('#loadingBar');
 
     return shadow(this, 'loadingBar', bar);
   },

web/ui_utils.js

@@ -15,17 +15,17 @@
 
 import { PDFJS } from 'pdfjs-lib';
 
-var CSS_UNITS = 96.0 / 72.0;
+const CSS_UNITS = 96.0 / 72.0;
-var DEFAULT_SCALE_VALUE = 'auto';
+const DEFAULT_SCALE_VALUE = 'auto';
-var DEFAULT_SCALE = 1.0;
+const DEFAULT_SCALE = 1.0;
-var MIN_SCALE = 0.25;
+const MIN_SCALE = 0.25;
-var MAX_SCALE = 10.0;
+const MAX_SCALE = 10.0;
-var UNKNOWN_SCALE = 0;
+const UNKNOWN_SCALE = 0;
-var MAX_AUTO_SCALE = 1.25;
+const MAX_AUTO_SCALE = 1.25;
-var SCROLLBAR_PADDING = 40;
+const SCROLLBAR_PADDING = 40;
-var VERTICAL_PADDING = 5;
+const VERTICAL_PADDING = 5;
-
+
-var RendererType = {
+const RendererType = {
   CANVAS: 'canvas',
   SVG: 'svg',
 };
@@ -44,7 +44,7 @@ function formatL10nValue(text, args) {
  * No-op implemetation of the localization service.
  * @implements {IL10n}
  */
-var NullL10n = {
+let NullL10n = {
   get(property, args, fallback) {
     return Promise.resolve(formatL10nValue(fallback, args));
   },
@@ -115,13 +115,13 @@ if (typeof PDFJSDev === 'undefined' ||
                     not required, true otherwise.
  */
 function getOutputScale(ctx) {
-  var devicePixelRatio = window.devicePixelRatio || 1;
+  let devicePixelRatio = window.devicePixelRatio || 1;
-  var backingStoreRatio = ctx.webkitBackingStorePixelRatio ||
+  let backingStoreRatio = ctx.webkitBackingStorePixelRatio ||
                           ctx.mozBackingStorePixelRatio ||
                           ctx.msBackingStorePixelRatio ||
                           ctx.oBackingStorePixelRatio ||
                           ctx.backingStorePixelRatio || 1;
-  var pixelRatio = devicePixelRatio / backingStoreRatio;
+  let pixelRatio = devicePixelRatio / backingStoreRatio;
   return {
     sx: pixelRatio,
     sy: pixelRatio,
@@ -137,20 +137,20 @@ function getOutputScale(ctx) {
  * @param {boolean} skipOverflowHiddenElements - Ignore elements that have
  *   the CSS rule `overflow: hidden;` set. The default is false.
  */
-function scrollIntoView(element, spot, skipOverflowHiddenElements) {
+function scrollIntoView(element, spot, skipOverflowHiddenElements = false) {
   // Assuming offsetParent is available (it's not available when viewer is in
   // hidden iframe or object). We have to scroll: if the offsetParent is not set
   // producing the error. See also animationStarted.
-  var parent = element.offsetParent;
+  let parent = element.offsetParent;
   if (!parent) {
     console.error('offsetParent is not set -- cannot scroll');
     return;
   }
-  var checkOverflow = skipOverflowHiddenElements || false;
+  let offsetY = element.offsetTop + element.clientTop;
-  var offsetY = element.offsetTop + element.clientTop;
+  let offsetX = element.offsetLeft + element.clientLeft;
-  var offsetX = element.offsetLeft + element.clientLeft;
   while (parent.clientHeight === parent.scrollHeight ||
-         (checkOverflow && getComputedStyle(parent).overflow === 'hidden')) {
+         (skipOverflowHiddenElements &&
+          getComputedStyle(parent).overflow === 'hidden')) {
     if (parent.dataset._scaleY) {
       offsetY /= parent.dataset._scaleY;
       offsetX /= parent.dataset._scaleX;
@@ -179,7 +179,7 @@ function scrollIntoView(element, spot, skipOverflowHiddenElements) {
  * PDF.js friendly one: with scroll debounce and scroll direction.
  */
 function watchScroll(viewAreaElement, callback) {
-  var debounceScroll = function debounceScroll(evt) {
+  let debounceScroll = function(evt) {
     if (rAF) {
       return;
     }
@@ -187,8 +187,8 @@ function watchScroll(viewAreaElement, callback) {
     rAF = window.requestAnimationFrame(function viewAreaElementScrolled() {
       rAF = null;
 
-      var currentY = viewAreaElement.scrollTop;
+      let currentY = viewAreaElement.scrollTop;
-      var lastY = state.lastY;
+      let lastY = state.lastY;
       if (currentY !== lastY) {
         state.down = currentY > lastY;
       }
@@ -197,13 +197,13 @@ function watchScroll(viewAreaElement, callback) {
     });
   };
 
-  var state = {
+  let state = {
     down: true,
     lastY: viewAreaElement.scrollTop,
     _eventHandler: debounceScroll,
   };
 
-  var rAF = null;
+  let rAF = null;
   viewAreaElement.addEventListener('scroll', debounceScroll, true);
   return state;
 }
@@ -212,12 +212,12 @@ function watchScroll(viewAreaElement, callback) {
  * Helper function to parse query string (e.g. ?param1=value&parm2=...).
  */
 function parseQueryString(query) {
-  var parts = query.split('&');
+  let parts = query.split('&');
-  var params = {};
+  let params = Object.create(null);
-  for (var i = 0, ii = parts.length; i < ii; ++i) {
+  for (let i = 0, ii = parts.length; i < ii; ++i) {
-    var param = parts[i].split('=');
+    let param = parts[i].split('=');
-    var key = param[0].toLowerCase();
+    let key = param[0].toLowerCase();
-    var value = param.length > 1 ? param[1] : null;
+    let value = param.length > 1 ? param[1] : null;
     params[decodeURIComponent(key)] = decodeURIComponent(value);
   }
   return params;
@@ -233,8 +233,8 @@ function parseQueryString(query) {
  *                   or |items.length| if no such element exists.
  */
 function binarySearchFirstItem(items, condition) {
-  var minIndex = 0;
+  let minIndex = 0;
-  var maxIndex = items.length - 1;
+  let maxIndex = items.length - 1;
 
   if (items.length === 0 || !condition(items[maxIndex])) {
     return items.length;
@@ -244,8 +244,8 @@ function binarySearchFirstItem(items, condition) {
   }
 
   while (minIndex < maxIndex) {
-    var currentIndex = (minIndex + maxIndex) >> 1;
+    let currentIndex = (minIndex + maxIndex) >> 1;
-    var currentItem = items[currentIndex];
+    let currentItem = items[currentIndex];
     if (condition(currentItem)) {
       maxIndex = currentIndex;
     } else {
@@ -267,21 +267,21 @@ function approximateFraction(x) {
   if (Math.floor(x) === x) {
     return [x, 1];
   }
-  var xinv = 1 / x;
+  let xinv = 1 / x;
-  var limit = 8;
+  let limit = 8;
   if (xinv > limit) {
     return [1, limit];
   } else if (Math.floor(xinv) === xinv) {
     return [1, xinv];
   }
 
-  var x_ = x > 1 ? xinv : x;
+  let x_ = x > 1 ? xinv : x;
   // a/b and c/d are neighbours in Farey sequence.
-  var a = 0, b = 1, c = 1, d = 1;
+  let a = 0, b = 1, c = 1, d = 1;
   // Limiting search to order 8.
   while (true) {
     // Generating next term in sequence (order of q).
-    var p = a + c, q = b + d;
+    let p = a + c, q = b + d;
     if (q > limit) {
       break;
     }
@@ -291,7 +291,7 @@ function approximateFraction(x) {
       a = p; b = q;
     }
   }
-  var result;
+  let result;
   // Select closest of the neighbours to x.
   if (x_ - a / b < c / d - x_) {
     result = x_ === x ? [a, b] : [b, a];
@@ -302,31 +302,31 @@ function approximateFraction(x) {
 }
 
 function roundToDivide(x, div) {
-  var r = x % div;
+  let r = x % div;
   return r === 0 ? x : Math.round(x - r + div);
 }
 
 /**
  * Generic helper to find out what elements are visible within a scroll pane.
  */
-function getVisibleElements(scrollEl, views, sortByVisibility) {
+function getVisibleElements(scrollEl, views, sortByVisibility = false) {
-  var top = scrollEl.scrollTop, bottom = top + scrollEl.clientHeight;
+  let top = scrollEl.scrollTop, bottom = top + scrollEl.clientHeight;
-  var left = scrollEl.scrollLeft, right = left + scrollEl.clientWidth;
+  let left = scrollEl.scrollLeft, right = left + scrollEl.clientWidth;
 
   function isElementBottomBelowViewTop(view) {
-    var element = view.div;
+    let element = view.div;
-    var elementBottom =
+    let elementBottom =
       element.offsetTop + element.clientTop + element.clientHeight;
     return elementBottom > top;
   }
 
-  var visible = [], view, element;
+  let visible = [], view, element;
-  var currentHeight, viewHeight, hiddenHeight, percentHeight;
+  let currentHeight, viewHeight, hiddenHeight, percentHeight;
-  var currentWidth, viewWidth;
+  let currentWidth, viewWidth;
-  var firstVisibleElementInd = (views.length === 0) ? 0 :
+  let firstVisibleElementInd = views.length === 0 ? 0 :
     binarySearchFirstItem(views, isElementBottomBelowViewTop);
 
-  for (var i = firstVisibleElementInd, ii = views.length; i < ii; i++) {
+  for (let i = firstVisibleElementInd, ii = views.length; i < ii; i++) {
     view = views[i];
     element = view.div;
     currentHeight = element.offsetTop + element.clientTop;
@@ -354,12 +354,12 @@ function getVisibleElements(scrollEl, views, sortByVisibility) {
     });
   }
 
-  var first = visible[0];
+  let first = visible[0];
-  var last = visible[visible.length - 1];
+  let last = visible[visible.length - 1];
 
   if (sortByVisibility) {
     visible.sort(function(a, b) {
-      var pc = a.percent - b.percent;
+      let pc = a.percent - b.percent;
       if (Math.abs(pc) > 0.001) {
         return -pc;
       }
@@ -372,12 +372,12 @@ function getVisibleElements(scrollEl, views, sortByVisibility) {
 /**
  * Event handler to suppress context menu.
  */
-function noContextMenuHandler(e) {
+function noContextMenuHandler(evt) {
-  e.preventDefault();
+  evt.preventDefault();
 }
 
 function isDataSchema(url) {
-  var i = 0, ii = url.length;
+  let i = 0, ii = url.length;
   while (i < ii && url[i].trim() === '') {
     i++;
   }
@@ -397,12 +397,12 @@ function getPDFFileNameFromURL(url, defaultFilename = 'document.pdf') {
                  'ignoring "data:" URL for performance reasons.');
     return defaultFilename;
   }
-  var reURI = /^(?:(?:[^:]+:)?\/\/[^\/]+)?([^?#]*)(\?[^#]*)?(#.*)?$/;
+  const reURI = /^(?:(?:[^:]+:)?\/\/[^\/]+)?([^?#]*)(\?[^#]*)?(#.*)?$/;
   //            SCHEME        HOST         1.PATH  2.QUERY   3.REF
   // Pattern to get last matching NAME.pdf
-  var reFilename = /[^\/?#=]+\.pdf\b(?!.*\.pdf\b)/i;
+  const reFilename = /[^\/?#=]+\.pdf\b(?!.*\.pdf\b)/i;
-  var splitURI = reURI.exec(url);
+  let splitURI = reURI.exec(url);
-  var suggestedFilename = reFilename.exec(splitURI[1]) ||
+  let suggestedFilename = reFilename.exec(splitURI[1]) ||
                           reFilename.exec(splitURI[2]) ||
                           reFilename.exec(splitURI[3]);
   if (suggestedFilename) {
@@ -412,7 +412,7 @@ function getPDFFileNameFromURL(url, defaultFilename = 'document.pdf') {
       try {
         suggestedFilename =
           reFilename.exec(decodeURIComponent(suggestedFilename))[0];
-      } catch (e) { // Possible (extremely rare) errors:
+      } catch (ex) { // Possible (extremely rare) errors:
         // URIError "Malformed URI", e.g. for "%AA.pdf"
         // TypeError "null has no properties", e.g. for "%2F.pdf"
       }
@@ -422,17 +422,17 @@ function getPDFFileNameFromURL(url, defaultFilename = 'document.pdf') {
 }
 
 function normalizeWheelEventDelta(evt) {
-  var delta = Math.sqrt(evt.deltaX * evt.deltaX + evt.deltaY * evt.deltaY);
+  let delta = Math.sqrt(evt.deltaX * evt.deltaX + evt.deltaY * evt.deltaY);
-  var angle = Math.atan2(evt.deltaY, evt.deltaX);
+  let angle = Math.atan2(evt.deltaY, evt.deltaX);
   if (-0.25 * Math.PI < angle && angle < 0.75 * Math.PI) {
     // All that is left-up oriented has to change the sign.
     delta = -delta;
   }
 
-  var MOUSE_DOM_DELTA_PIXEL_MODE = 0;
+  const MOUSE_DOM_DELTA_PIXEL_MODE = 0;
-  var MOUSE_DOM_DELTA_LINE_MODE = 1;
+  const MOUSE_DOM_DELTA_LINE_MODE = 1;
-  var MOUSE_PIXELS_PER_LINE = 30;
+  const MOUSE_PIXELS_PER_LINE = 30;
-  var MOUSE_LINES_PER_PAGE = 30;
+  const MOUSE_LINES_PER_PAGE = 30;
 
   // Converts delta to per-page units
   if (evt.deltaMode === MOUSE_DOM_DELTA_PIXEL_MODE) {
@@ -444,8 +444,8 @@ function normalizeWheelEventDelta(evt) {
 }
 
 function cloneObj(obj) {
-  var result = {};
+  let result = Object.create(null);
-  for (var i in obj) {
+  for (let i in obj) {
     if (Object.prototype.hasOwnProperty.call(obj, i)) {
       result[i] = obj[i];
     }
@@ -456,91 +456,87 @@ function cloneObj(obj) {
 /**
  * Promise that is resolved when DOM window becomes visible.
  */
-var animationStarted = new Promise(function (resolve) {
+let animationStarted = new Promise(function (resolve) {
   window.requestAnimationFrame(resolve);
 });
 
 /**
  * (deprecated) External localization service.
  */
-var mozL10n;
+let mozL10n;
 
 /**
  * (deprecated) Promise that is resolved when UI localization is finished.
  */
-var localized = Promise.resolve();
+let localized = Promise.resolve();
 
 /**
  * Simple event bus for an application. Listeners are attached using the
  * `on` and `off` methods. To raise an event, the `dispatch` method shall be
  * used.
  */
-var EventBus = (function EventBusClosure() {
+class EventBus {
-  function EventBus() {
+  constructor() {
     this._listeners = Object.create(null);
   }
-  EventBus.prototype = {
+
-    on: function EventBus_on(eventName, listener) {
+  on(eventName, listener) {
-      var eventListeners = this._listeners[eventName];
+    let eventListeners = this._listeners[eventName];
     if (!eventListeners) {
       eventListeners = [];
       this._listeners[eventName] = eventListeners;
     }
     eventListeners.push(listener);
-    },
+  }
-    off: function EventBus_on(eventName, listener) {
+
-      var eventListeners = this._listeners[eventName];
+  off(eventName, listener) {
-      var i;
+    let eventListeners = this._listeners[eventName];
+    let i;
     if (!eventListeners || ((i = eventListeners.indexOf(listener)) < 0)) {
       return;
     }
     eventListeners.splice(i, 1);
-    },
+  }
-    dispatch: function EventBus_dispath(eventName) {
+
-      var eventListeners = this._listeners[eventName];
+  dispatch(eventName) {
+    let eventListeners = this._listeners[eventName];
     if (!eventListeners || eventListeners.length === 0) {
       return;
     }
     // Passing all arguments after the eventName to the listeners.
-      var args = Array.prototype.slice.call(arguments, 1);
+    let args = Array.prototype.slice.call(arguments, 1);
     // Making copy of the listeners array in case if it will be modified
     // during dispatch.
     eventListeners.slice(0).forEach(function (listener) {
       listener.apply(null, args);
     });
-    },
+  }
-  };
+}
-  return EventBus;
-})();
-
-var ProgressBar = (function ProgressBarClosure() {
 
-  function clamp(v, min, max) {
+function clamp(v, min, max) {
   return Math.min(Math.max(v, min), max);
-  }
+}
 
-  function ProgressBar(id, opts) {
+class ProgressBar {
+  constructor(id, { height, width, units, } = {}) {
     this.visible = true;
 
     // Fetch the sub-elements for later.
     this.div = document.querySelector(id + ' .progress');
-
     // Get the loading bar element, so it can be resized to fit the viewer.
     this.bar = this.div.parentNode;
 
     // Get options, with sensible defaults.
-    this.height = opts.height || 100;
+    this.height = height || 100;
-    this.width = opts.width || 100;
+    this.width = width || 100;
-    this.units = opts.units || '%';
+    this.units = units || '%';
 
     // Initialize heights.
     this.div.style.height = this.height + this.units;
     this.percent = 0;
   }
 
-  ProgressBar.prototype = {
+  _updateBar() {
-
-    updateBar: function ProgressBar_updateBar() {
     if (this._indeterminate) {
       this.div.classList.add('indeterminate');
       this.div.style.width = this.width + this.units;
@@ -548,52 +544,50 @@ var ProgressBar = (function ProgressBarClosure() {
     }
 
     this.div.classList.remove('indeterminate');
-      var progressSize = this.width * this._percent / 100;
+    let progressSize = this.width * this._percent / 100;
     this.div.style.width = progressSize + this.units;
-    },
+  }
 
   get percent() {
     return this._percent;
-    },
+  }
 
   set percent(val) {
     this._indeterminate = isNaN(val);
     this._percent = clamp(val, 0, 100);
-      this.updateBar();
+    this._updateBar();
-    },
+  }
 
-    setWidth: function ProgressBar_setWidth(viewer) {
+  setWidth(viewer) {
-      if (viewer) {
+    if (!viewer) {
-        var container = viewer.parentNode;
+      return;
-        var scrollbarWidth = container.offsetWidth - viewer.offsetWidth;
+    }
+    let container = viewer.parentNode;
+    let scrollbarWidth = container.offsetWidth - viewer.offsetWidth;
     if (scrollbarWidth > 0) {
       this.bar.setAttribute('style', 'width: calc(100% - ' +
                                      scrollbarWidth + 'px);');
     }
   }
-    },
 
-    hide: function ProgressBar_hide() {
+  hide() {
     if (!this.visible) {
       return;
     }
     this.visible = false;
     this.bar.classList.add('hidden');
     document.body.classList.remove('loadingInProgress');
-    },
+  }
 
-    show: function ProgressBar_show() {
+  show() {
     if (this.visible) {
       return;
     }
     this.visible = true;
     document.body.classList.add('loadingInProgress');
     this.bar.classList.remove('hidden');
-    },
+  }
-  };
+}
-
-  return ProgressBar;
-})();
 
 export {
   CSS_UNITS,