Use shorter arrow functions where possible

.eslintrc

@@ -242,9 +242,9 @@
     }],
 
     // ECMAScript 6
+    "arrow-body-style": ["error", "as-needed"],
     "constructor-super": "error",
     "no-class-assign": "error",
-    "no-confusing-arrow": "error",
     "no-const-assign": "error",
     "no-dupe-class-members": "error",
     "no-duplicate-imports": "error",

src/core/annotation.js

@@ -79,6 +79,7 @@ class AnnotationFactory {
       // with "GoToE" actions, from throwing and thus breaking parsing:
       pdfManager.ensureCatalog("attachments"),
     ]).then(
+      // eslint-disable-next-line arrow-body-style
       ([acroForm, xfaDatasets, structTreeRoot, baseUrl, attachments]) => {
         return {
           pdfManager,
@@ -2133,11 +2134,8 @@ class WidgetAnnotation extends Annotation {
       value,
     };
 
-    const encoder = val => {
-      return isAscii(val)
-        ? val
-        : stringToUTF16String(val, /* bigEndian = */ true);
-    };
+    const encoder = val =>
+      isAscii(val) ? val : stringToUTF16String(val, /* bigEndian = */ true);
     dict.set("V", Array.isArray(value) ? value.map(encoder) : encoder(value));
     this.amendSavedDict(annotationStorage, dict);
 
@@ -4824,9 +4822,7 @@ class StampAnnotation extends MarkupAnnotation {
 
     const jpegBufferPromise = canvas
       .convertToBlob({ type: "image/jpeg", quality: 1 })
-      .then(blob => {
-        return blob.arrayBuffer();
-      });
+      .then(blob => blob.arrayBuffer());
 
     const xobjectName = Name.get("XObject");
     const imageName = Name.get("Image");

src/core/catalog.js

@@ -893,14 +893,13 @@ class Catalog {
         case "PrintPageRange":
           // The number of elements must be even.
           if (Array.isArray(value) && value.length % 2 === 0) {
-            const isValid = value.every((page, i, arr) => {
-              return (
+            const isValid = value.every(
+              (page, i, arr) =>
                 Number.isInteger(page) &&
                 page > 0 &&
                 (i === 0 || page >= arr[i - 1]) &&
                 page <= this.numPages
-              );
-            });
+            );
             if (isValid) {
               prefValue = value;
             }

src/core/cmap.js

@@ -691,9 +691,9 @@ async function createBuiltInCMap(name, fetchBuiltInCMap) {
   const cMap = new CMap(true);
 
   if (compressionType === CMapCompressionType.BINARY) {
-    return new BinaryCMapReader().process(cMapData, cMap, useCMap => {
-      return extendCMap(cMap, fetchBuiltInCMap, useCMap);
-    });
+    return new BinaryCMapReader().process(cMapData, cMap, useCMap =>
+      extendCMap(cMap, fetchBuiltInCMap, useCMap)
+    );
   }
   if (compressionType === CMapCompressionType.NONE) {
     const lexer = new Lexer(new Stream(cMapData));

src/core/document.js

@@ -1577,6 +1577,7 @@ class PDFDocument {
     } else {
       promise = catalog.getPageDict(pageIndex);
     }
+    // eslint-disable-next-line arrow-body-style
     promise = promise.then(([pageDict, ref]) => {
       return new Page({
         pdfManager: this.pdfManager,

src/core/evaluator.js

@@ -1039,14 +1039,15 @@ class PartialEvaluator {
 
             return translated;
           })
-          .catch(reason => {
-            return new TranslatedFont({
-              loadedName: "g_font_error",
-              font: new ErrorFont(`Type3 font load error: ${reason}`),
-              dict: translated.font,
-              evaluatorOptions: this.options,
-            });
-          });
+          .catch(
+            reason =>
+              new TranslatedFont({
+                loadedName: "g_font_error",
+                font: new ErrorFont(`Type3 font load error: ${reason}`),
+                dict: translated.font,
+                evaluatorOptions: this.options,
+              })
+          );
       })
       .then(translated => {
         state.font = translated.font;
@@ -1129,6 +1130,7 @@ class PartialEvaluator {
         case "Font":
           isSimpleGState = false;
 
+          // eslint-disable-next-line arrow-body-style
           promise = promise.then(() => {
             return this.handleSetFont(
               resources,
@@ -1154,6 +1156,7 @@ class PartialEvaluator {
           if (value instanceof Dict) {
             isSimpleGState = false;
 
+            // eslint-disable-next-line arrow-body-style
             promise = promise.then(() => {
               return this.handleSMask(
                 value,
@@ -1214,6 +1217,7 @@ class PartialEvaluator {
     fallbackFontDict = null,
     cssFontInfo = null
   ) {
+    // eslint-disable-next-line arrow-body-style
     const errorFont = async () => {
       return new TranslatedFont({
         loadedName: "g_font_error",

src/core/fonts.js

@@ -2093,19 +2093,15 @@ class Font {
           endOffset: 0,
         });
       }
-      locaEntries.sort((a, b) => {
-        return a.offset - b.offset;
-      });
+      locaEntries.sort((a, b) => a.offset - b.offset);
       // Now the offsets are sorted, calculate the end offset of each glyph.
       // The last loca entry's endOffset is not calculated since it's the end
       // of the data and will be stored on the previous entry's endOffset.
       for (i = 0; i < numGlyphs; i++) {
         locaEntries[i].endOffset = locaEntries[i + 1].offset;
       }
       // Re-sort so glyphs aren't out of order.
-      locaEntries.sort((a, b) => {
-        return a.index - b.index;
-      });
+      locaEntries.sort((a, b) => a.index - b.index);
       // Calculate the endOffset of the "first" glyph correctly when there are
       // *multiple* empty ones at the start of the data (fixes issue14618.pdf).
       for (i = 0; i < numGlyphs; i++) {

src/core/writer.js

@@ -344,10 +344,9 @@ async function incrementalUpdate({
 
   // Add a ref for the new xref and sort them
   newRefs.push({ ref: refForXrefTable, data: "" });
-  newRefs = newRefs.sort((a, b) => {
-    // compare the refs
-    return a.ref.num - b.ref.num;
-  });
+  newRefs = newRefs.sort(
+    (a, b) => /* compare the refs */ a.ref.num - b.ref.num
+  );
 
   const xrefTableData = [[0, 1, 0xffff]];
   const indexes = [0, 1];

src/core/xfa/utils.js

@@ -129,12 +129,10 @@ function getRelevant(data) {
   return data
     .trim()
     .split(/\s+/)
-    .map(e => {
-      return {
-        excluded: e[0] === "-",
-        viewname: e.substring(1),
-      };
-    });
+    .map(e => ({
+      excluded: e[0] === "-",
+      viewname: e.substring(1),
+    }));
 }
 
 function getColor(data, def = [0, 0, 0]) {

src/display/annotation_layer.js

@@ -1838,9 +1838,10 @@ class ChoiceWidgetAnnotationElement extends WidgetAnnotationElement {
 
     const getItems = event => {
       const options = event.target.options;
-      return Array.prototype.map.call(options, option => {
-        return { displayValue: option.textContent, exportValue: option.value };
-      });
+      return Array.prototype.map.call(options, option => ({
+        displayValue: option.textContent,
+        exportValue: option.value,
+      }));
     };
 
     if (this.enableScripting && this.hasJSActions) {

src/display/api.js

@@ -771,19 +771,13 @@ class PDFDocumentProxy {
     if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
       // For testing purposes.
       Object.defineProperty(this, "getXFADatasets", {
-        value: () => {
-          return this._transport.getXFADatasets();
-        },
+        value: () => this._transport.getXFADatasets(),
       });
       Object.defineProperty(this, "getXRefPrevValue", {
-        value: () => {
-          return this._transport.getXRefPrevValue();
-        },
+        value: () => this._transport.getXRefPrevValue(),
       });
       Object.defineProperty(this, "getAnnotArray", {
-        value: pageIndex => {
-          return this._transport.getAnnotArray(pageIndex);
-        },
+        value: pageIndex => this._transport.getAnnotArray(pageIndex),
       });
     }
   }
@@ -1628,9 +1622,7 @@ class PDFPageProxy {
     if (this._transport._htmlForXfa) {
       // TODO: We need to revisit this once the XFA foreground patch lands and
       // only do this for non-foreground XFA.
-      return this.getXfa().then(xfa => {
-        return XfaText.textContent(xfa);
-      });
+      return this.getXfa().then(xfa => XfaText.textContent(xfa));
     }
     const readableStream = this.streamTextContent(params);
 
@@ -2358,21 +2350,16 @@ class WorkerTransport {
     if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
       // For testing purposes.
       Object.defineProperty(this, "getXFADatasets", {
-        value: () => {
-          return this.messageHandler.sendWithPromise("GetXFADatasets", null);
-        },
+        value: () =>
+          this.messageHandler.sendWithPromise("GetXFADatasets", null),
       });
       Object.defineProperty(this, "getXRefPrevValue", {
-        value: () => {
-          return this.messageHandler.sendWithPromise("GetXRefPrevValue", null);
-        },
+        value: () =>
+          this.messageHandler.sendWithPromise("GetXRefPrevValue", null),
       });
       Object.defineProperty(this, "getAnnotArray", {
-        value: pageIndex => {
-          return this.messageHandler.sendWithPromise("GetAnnotArray", {
-            pageIndex,
-          });
-        },
+        value: pageIndex =>
+          this.messageHandler.sendWithPromise("GetAnnotArray", { pageIndex }),
       });
     }
   }
@@ -2737,9 +2724,7 @@ class WorkerTransport {
 
           this.fontLoader
             .bind(font)
-            .catch(reason => {
-              return messageHandler.sendWithPromise("FontFallback", { id });
-            })
+            .catch(() => messageHandler.sendWithPromise("FontFallback", { id }))
             .finally(() => {
               if (!params.fontExtraProperties && font.data) {
                 // Immediately release the `font.data` property once the font
@@ -3013,9 +2998,7 @@ class WorkerTransport {
   getOptionalContentConfig() {
     return this.messageHandler
       .sendWithPromise("GetOptionalContentConfig", null)
-      .then(results => {
-        return new OptionalContentConfig(results);
-      });
+      .then(results => new OptionalContentConfig(results));
   }
 
   getPermissions() {
@@ -3030,14 +3013,12 @@ class WorkerTransport {
     }
     const promise = this.messageHandler
       .sendWithPromise(name, null)
-      .then(results => {
-        return {
-          info: results[0],
-          metadata: results[1] ? new Metadata(results[1]) : null,
-          contentDispositionFilename: this._fullReader?.filename ?? null,
-          contentLength: this._fullReader?.contentLength ?? null,
-        };
-      });
+      .then(results => ({
+        info: results[0],
+        metadata: results[1] ? new Metadata(results[1]) : null,
+        contentDispositionFilename: this._fullReader?.filename ?? null,
+        contentLength: this._fullReader?.contentLength ?? null,
+      }));
     this.#methodPromises.set(name, promise);
     return promise;
   }
@@ -3192,9 +3173,7 @@ class RenderTask {
     if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
       // For testing purposes.
       Object.defineProperty(this, "getOperatorList", {
-        value: () => {
-          return this.#internalRenderTask.operatorList;
-        },
+        value: () => this.#internalRenderTask.operatorList,
       });
     }
   }

src/display/canvas.js

@@ -2359,8 +2359,8 @@ class CanvasGraphics {
       const color = IR[1];
       const baseTransform = this.baseTransform || getCurrentTransform(this.ctx);
       const canvasGraphicsFactory = {
-        createCanvasGraphics: ctx => {
-          return new CanvasGraphics(
+        createCanvasGraphics: ctx =>
+          new CanvasGraphics(
             ctx,
             this.commonObjs,
             this.objs,
@@ -2370,8 +2370,7 @@ class CanvasGraphics {
               optionalContentConfig: this.optionalContentConfig,
               markedContentStack: this.markedContentStack,
             }
-          );
-        },
+          ),
       };
       pattern = new TilingPattern(
         IR,

src/display/display_utils.js

@@ -466,15 +466,13 @@ class DOMCMapReaderFactory extends BaseCMapReaderFactory {
     return fetchData(
       url,
       /* type = */ this.isCompressed ? "arraybuffer" : "text"
-    ).then(data => {
-      return {
-        cMapData:
-          data instanceof ArrayBuffer
-            ? new Uint8Array(data)
-            : stringToBytes(data),
-        compressionType,
-      };
-    });
+    ).then(data => ({
+      cMapData:
+        data instanceof ArrayBuffer
+          ? new Uint8Array(data)
+          : stringToBytes(data),
+      compressionType,
+    }));
   }
 }
 
@@ -483,9 +481,9 @@ class DOMStandardFontDataFactory extends BaseStandardFontDataFactory {
    * @ignore
    */
   _fetchData(url) {
-    return fetchData(url, /* type = */ "arraybuffer").then(data => {
-      return new Uint8Array(data);
-    });
+    return fetchData(url, /* type = */ "arraybuffer").then(
+      data => new Uint8Array(data)
+    );
   }
 }
 

src/display/editor/tools.js

@@ -606,15 +606,14 @@ class AnnotationEditorUIManager {
   static get _keyboardManager() {
     const proto = AnnotationEditorUIManager.prototype;
 
-    const arrowChecker = self => {
-      // If the focused element is an input, we don't want to handle the arrow.
-      // For example, sliders can be controlled with the arrow keys.
-      return (
-        self.#container.contains(document.activeElement) &&
-        document.activeElement.tagName !== "BUTTON" &&
-        self.hasSomethingToControl()
-      );
-    };
+    /**
+     * If the focused element is an input, we don't want to handle the arrow.
+     * For example, sliders can be controlled with the arrow keys.
+     */
+    const arrowChecker = self =>
+      self.#container.contains(document.activeElement) &&
+      document.activeElement.tagName !== "BUTTON" &&
+      self.hasSomethingToControl();
 
     const textInputChecker = (_self, { target: el }) => {
       if (el instanceof HTMLInputElement) {