Enable the no-lonely-if ESLint rule

These changes were mostly done automatically, using `gulp lint --fix`, and only a few spots with comments needed manual tweaking; please see https://eslint.org/docs/latest/rules/no-lonely-if

.eslintrc

@@ -139,6 +139,7 @@
     "no-implied-eval": "error",
     "no-iterator": "error",
     "no-lone-blocks": "error",
+    "no-lonely-if": "error",
     "no-multi-str": "error",
     "no-new-func": "error",
     "no-new-wrappers": "error",

external/builder/builder.mjs

@@ -198,8 +198,7 @@ function preprocess(inFilename, outFilename, defines) {
           }
           break;
       }
-    } else {
-      if (state === STATE_NONE) {
+    } else if (state === STATE_NONE) {
       writeLine(line);
     } else if (
       (state === STATE_IF_TRUE || state === STATE_ELSE_TRUE) &&
@@ -214,7 +213,6 @@ function preprocess(inFilename, outFilename, defines) {
       );
     }
   }
-  }
   if (state !== STATE_NONE || stack.length !== 0) {
     throw new Error(
       "Missing #endif in preprocessor for " + fs.realpathSync(inFilename)

external/importL10n/locales.mjs

@@ -100,11 +100,9 @@ function downloadLanguageFiles(root, langCode) {
               resolve();
             }
           });
-        } else {
-          if (--downloadsLeft === 0) {
+        } else if (--downloadsLeft === 0) {
           resolve();
         }
-        }
       });
     });
   });

src/core/annotation.js

@@ -2698,8 +2698,7 @@ class TextWidgetAnnotation extends WidgetAnnotation {
           lastSpacePosInStringEnd = end;
           lastSpacePos = i;
         }
-      } else {
-        if (currentWidth + glyphWidth > width) {
+      } else if (currentWidth + glyphWidth > width) {
         // We must break to the last white position (if available)
         if (lastSpacePosInStringStart !== -1) {
           chunks.push(line.substring(startChunk, lastSpacePosInStringEnd));
@@ -2717,7 +2716,6 @@ class TextWidgetAnnotation extends WidgetAnnotation {
         currentWidth += glyphWidth;
       }
     }
-    }
 
     if (startChunk < line.length) {
       chunks.push(line.substring(startChunk, line.length));

src/core/bidi.js

@@ -353,13 +353,10 @@ function bidi(str, startLevel = -1, vertical = false) {
       } else if (t === "AN" || t === "EN") {
         levels[i] += 2;
       }
-    } else {
-      // isOdd
-      if (t === "L" || t === "AN" || t === "EN") {
+    } else if (/* isOdd && */ t === "L" || t === "AN" || t === "EN") {
       levels[i] += 1;
     }
   }
-  }
 
   /*
    L1. On each line, reset the embedding level of the following characters to

src/core/chunked_stream.js

@@ -207,7 +207,7 @@ class ChunkedStream extends Stream {
       if (start + length > this.progressiveDataLength) {
         this.ensureRange(start, start + length);
       }
-    } else {
+    } else if (start >= this.progressiveDataLength) {
       // When the `length` is undefined you do *not*, under any circumstances,
       // want to fallback on calling `this.ensureRange(start, this.end)` since
       // that would force the *entire* PDF file to be loaded, thus completely
@@ -217,10 +217,8 @@ class ChunkedStream extends Stream {
       // time/resources during e.g. parsing, since `MissingDataException`s will
       // require data to be re-parsed, which we attempt to minimize by at least
       // checking that the *beginning* of the data is available here.
-      if (start >= this.progressiveDataLength) {
       this.ensureByte(start);
     }
-    }
 
     function ChunkedStreamSubstream() {}
     ChunkedStreamSubstream.prototype = Object.create(this);

src/core/colorspace.js

@@ -206,23 +206,13 @@ class ColorSpace {
           rgbBuf[rgbPos++] = colorMap[key + 2];
         }
       }
-    } else {
-      if (!needsResizing) {
+    } else if (!needsResizing) {
       // Fill in the RGB values directly into |dest|.
-        this.getRgbBuffer(
-          comps,
-          0,
-          width * actualHeight,
-          dest,
-          0,
-          bpc,
-          alpha01
-        );
+      this.getRgbBuffer(comps, 0, width * actualHeight, dest, 0, bpc, alpha01);
     } else {
       rgbBuf = new Uint8ClampedArray(count * 3);
       this.getRgbBuffer(comps, 0, count, rgbBuf, 0, bpc, /* alpha01 = */ 0);
     }
-    }
 
     if (rgbBuf) {
       if (needsResizing) {

src/core/font_renderer.js

@@ -211,15 +211,13 @@ function compileGlyf(code, cmds, font) {
           arg2 = getUint16(code, i + 2);
         }
         i += 4;
-      } else {
-        if (flags & 0x02) {
+      } else if (flags & 0x02) {
         arg1 = getInt8(code, i++);
         arg2 = getInt8(code, i++);
       } else {
         arg1 = code[i++];
         arg2 = code[i++];
       }
-      }
       if (flags & 0x02) {
         x = arg1;
         y = arg2;

src/core/glyf.js

@@ -619,8 +619,7 @@ class CompositeGlyph {
       ) {
         size += 2;
       }
-    } else {
-      if (
+    } else if (
       !(
         this.argument1 >= 0 &&
         this.argument1 <= 255 &&
@@ -630,7 +629,6 @@ class CompositeGlyph {
     ) {
       size += 2;
     }
-    }
 
     return size;
   }
@@ -650,8 +648,7 @@ class CompositeGlyph {
       ) {
         this.flags |= ARG_1_AND_2_ARE_WORDS;
       }
-    } else {
-      if (
+    } else if (
       !(
         this.argument1 >= 0 &&
         this.argument1 <= 255 &&
@@ -661,7 +658,6 @@ class CompositeGlyph {
     ) {
       this.flags |= ARG_1_AND_2_ARE_WORDS;
     }
-    }
 
     buf.setUint16(pos, this.flags);
     buf.setUint16(pos + 2, this.glyphIndex);

src/core/xfa/template.js

@@ -3662,13 +3662,11 @@ class Line extends XFAObject {
     } else if (parent.h <= thickness) {
       [x1, y1, x2, y2] = [0, "50%", "100%", "50%"];
       height = style.strokeWidth;
-    } else {
-      if (this.slope === "\\") {
+    } else if (this.slope === "\\") {
       [x1, y1, x2, y2] = [0, 0, "100%", "100%"];
     } else {
       [x1, y1, x2, y2] = [0, "100%", "100%", 0];
     }
-    }
 
     const line = {
       name: "line",

src/display/svg.js

@@ -432,11 +432,9 @@ function pm(m) {
       const a = (Math.acos(m[0]) * 180) / Math.PI;
       return `rotate(${pf(a)})`;
     }
-  } else {
-    if (m[0] === 1 && m[1] === 0 && m[2] === 0 && m[3] === 1) {
+  } else if (m[0] === 1 && m[1] === 0 && m[2] === 0 && m[3] === 1) {
     return `translate(${pf(m[4])} ${pf(m[5])})`;
   }
-  }
   return (
     `matrix(${pf(m[0])} ${pf(m[1])} ${pf(m[2])} ${pf(m[3])} ${pf(m[4])} ` +
     `${pf(m[5])})`

src/scripting_api/field.js

@@ -127,13 +127,11 @@ class Field extends PDFObject {
       indices.forEach(i => {
         this._value.push(this._items[i].displayValue);
       });
-    } else {
-      if (indices.length > 0) {
+    } else if (indices.length > 0) {
       indices = indices.splice(1, indices.length - 1);
       this._currentValueIndices = indices[0];
       this._value = this._items[this._currentValueIndices];
     }
-    }
     this._send({ id: this._id, indices });
   }
 
@@ -389,13 +387,11 @@ class Field extends PDFObject {
           --this._currentValueIndices[index];
         }
       }
-    } else {
-      if (this._currentValueIndices === nIdx) {
+    } else if (this._currentValueIndices === nIdx) {
       this._currentValueIndices = this.numItems > 0 ? 0 : -1;
     } else if (this._currentValueIndices > nIdx) {
       --this._currentValueIndices;
     }
-    }
 
     this._send({ id: this._id, remove: nIdx });
   }

web/pdf_find_controller.js

@@ -623,12 +623,11 @@ class PDFFindController {
       if (newQuery !== prevQuery) {
         return true;
       }
-    } else {
-      // Array
-      if (JSON.stringify(newQuery) !== JSON.stringify(prevQuery)) {
+    } else if (
+      /* isArray && */ JSON.stringify(newQuery) !== JSON.stringify(prevQuery)
+    ) {
       return true;
     }
-    }
 
     switch (state.type) {
       case "again":

web/pdf_link_service.js

@@ -378,8 +378,7 @@ class PDFLinkService {
             zoomArgs.length > 2 ? zoomArgs[2] | 0 : null,
             zoomArgNumber ? zoomArgNumber / 100 : zoomArg,
           ];
-        } else {
-          if (zoomArg === "Fit" || zoomArg === "FitB") {
+        } else if (zoomArg === "Fit" || zoomArg === "FitB") {
           dest = [null, { name: zoomArg }];
         } else if (
           zoomArg === "FitH" ||
@@ -413,7 +412,6 @@ class PDFLinkService {
           );
         }
       }
-      }
       if (dest) {
         this.pdfViewer.scrollPageIntoView({
           pageNumber: pageNumber || this.page,

web/preferences.js

@@ -128,11 +128,9 @@ class BasePreferences {
           `Set preference: "${value}" is a ${valueType}, expected a ${defaultType}.`
         );
       }
-    } else {
-      if (valueType === "number" && !Number.isInteger(value)) {
+    } else if (valueType === "number" && !Number.isInteger(value)) {
       throw new Error(`Set preference: "${value}" must be an integer.`);
     }
-    }
 
     this.#prefs[name] = value;
     return this._writeToStorage(this.#prefs).catch(reason => {