Add @typescript-eslint/prefer-nullish-coalescing eslint rule

addons/addon-image/src/ImageAddon.ts

@@ -90,7 +90,7 @@ export class ImageAddon implements ITerminalAddon , IImageApi {
       // windowOptions.getCellSizePixels = true;
       // windowOptions.getWinSizeChars = true;
       // terminal.setOption('windowOptions', windowOptions);
-      const windowOps = terminal.options.windowOptions || {};
+      const windowOps = terminal.options.windowOptions ?? {};
       windowOps.getWinSizePixels = true;
       windowOps.getCellSizePixels = true;
       windowOps.getWinSizeChars = true;

addons/addon-image/src/ImageRenderer.ts

@@ -38,7 +38,7 @@ export class ImageRenderer extends Disposable implements IDisposable {
      * Only the DOM output canvas should be on the terminal's document,
      * which gets explicitly checked in `insertLayerToDom`.
      */
-    const canvas = (localDocument || document).createElement('canvas');
+    const canvas = (localDocument ?? document).createElement('canvas');
     canvas.width = width | 0;
     canvas.height = height | 0;
     return canvas;
@@ -242,7 +242,7 @@ export class ImageRenderer extends Disposable implements IDisposable {
       }
       if (!this._placeholder) return;
       this._ctx.drawImage(
-        this._placeholderBitmap || this._placeholder!,
+        this._placeholderBitmap ?? this._placeholder!,
         col * width,
         (row * height) % 2 ? 0 : 1,  // needs %2 offset correction
         width * count,

addons/addon-image/src/ImageStorage.ts

@@ -381,7 +381,7 @@ export class ImageStorage implements IDisposable {
       if (!line) return;
       for (let col = 0; col < cols; ++col) {
         if (line.getBg(col) & BgFlags.HAS_EXTENDED) {
-          let e: IExtendedAttrsImage = line._extendedAttrs[col] || EMPTY_ATTRS;
+          let e: IExtendedAttrsImage = line._extendedAttrs[col] ?? EMPTY_ATTRS;
           const imageId = e.imageId;
           if (imageId === undefined || imageId === -1) {
             continue;
@@ -400,7 +400,7 @@ export class ImageStorage implements IDisposable {
             while (
               ++col < cols
               && (line.getBg(col) & BgFlags.HAS_EXTENDED)
-              && (e = line._extendedAttrs[col] || EMPTY_ATTRS)
+              && (e = line._extendedAttrs[col] ?? EMPTY_ATTRS)
               && (e.imageId === imageId)
               && (e.tileId === startTile + count)
             ) {
@@ -442,7 +442,7 @@ export class ImageStorage implements IDisposable {
     for (let row = 0; row < rows; ++row) {
       const line = buffer.lines.get(row) as IBufferLineExt;
       if (line.getBg(oldCol) & BgFlags.HAS_EXTENDED) {
-        const e: IExtendedAttrsImage = line._extendedAttrs[oldCol] || EMPTY_ATTRS;
+        const e: IExtendedAttrsImage = line._extendedAttrs[oldCol] ?? EMPTY_ATTRS;
         const imageId = e.imageId;
         if (imageId === undefined || imageId === -1) {
           continue;
@@ -487,7 +487,7 @@ export class ImageStorage implements IDisposable {
     const buffer = this._terminal._core.buffer;
     const line = buffer.lines.get(y) as IBufferLineExt;
     if (line && line.getBg(x) & BgFlags.HAS_EXTENDED) {
-      const e: IExtendedAttrsImage = line._extendedAttrs[x] || EMPTY_ATTRS;
+      const e: IExtendedAttrsImage = line._extendedAttrs[x] ?? EMPTY_ATTRS;
       if (e.imageId && e.imageId !== -1) {
         const orig = this._images.get(e.imageId)?.orig;
         if (window.ImageBitmap && orig instanceof ImageBitmap) {
@@ -507,7 +507,7 @@ export class ImageStorage implements IDisposable {
     const buffer = this._terminal._core.buffer;
     const line = buffer.lines.get(y) as IBufferLineExt;
     if (line && line.getBg(x) & BgFlags.HAS_EXTENDED) {
-      const e: IExtendedAttrsImage = line._extendedAttrs[x] || EMPTY_ATTRS;
+      const e: IExtendedAttrsImage = line._extendedAttrs[x] ?? EMPTY_ATTRS;
       if (e.imageId && e.imageId !== -1 && e.tileId !== -1) {
         const spec = this._images.get(e.imageId);
         if (spec) {

addons/addon-ligatures/src/LigaturesAddon.ts

@@ -22,7 +22,7 @@ export class LigaturesAddon implements ITerminalAddon , ILigaturesApi {
 
   constructor(options?: Partial<ILigatureOptions>) {
     // Source: calt set from https://github.com/be5invis/Iosevka?tab=readme-ov-file#ligations
-    this._fallbackLigatures = (options?.fallbackLigatures || [
+    this._fallbackLigatures = (options?.fallbackLigatures ?? [
       '<--', '<---', '<<-', '<-', '->', '->>', '-->', '--->',
       '<==', '<===', '<<=', '<=', '=>', '=>>', '==>', '===>', '>=', '>>=',
       '<->', '<-->', '<--->', '<---->', '<=>', '<==>', '<===>', '<====>', '::', ':::',

addons/addon-ligatures/src/font.ts

@@ -80,9 +80,7 @@ export default async function load(fontFamily: string, cacheSize: number): Promi
         console.error(err.name, err.message);
       }
     }
-    if (!fontsPromise) {
-      fontsPromise = Promise.resolve({});
-    }
+    fontsPromise ??= Promise.resolve({});
   }
 
   const fonts = await fontsPromise;

addons/addon-ligatures/src/fontLigatures/processors/helper.ts

@@ -52,12 +52,10 @@ export function processLookaheadPosition(
     }
     processedEntries.add(currentEntry.entry);
 
-    if (!currentEntry.entry.forward) {
-      currentEntry.entry.forward = {
-        individual: {},
-        range: []
-      };
-    }
+    currentEntry.entry.forward ??= {
+      individual: {},
+      range: []
+    };
 
     // All glyphs at this position share ONE entry - lookahead just needs to match,
     // all paths lead to the same result
@@ -97,12 +95,10 @@ export function processBacktrackPosition(
     }
     processedEntries.add(currentEntry.entry);
 
-    if (!currentEntry.entry.reverse) {
-      currentEntry.entry.reverse = {
-        individual: {},
-        range: []
-      };
-    }
+    currentEntry.entry.reverse ??= {
+      individual: {},
+      range: []
+    };
 
     // All glyphs at this position share ONE entry - backtrack just needs to match,
     // all paths lead to the same result

addons/addon-ligatures/src/fontLigatures/processors/substitution.ts

@@ -54,9 +54,6 @@ export function getIndividualSubstitutionGlyph(table: SubstitutionTable, glyphId
       return (glyphId + table.deltaGlyphId) % (2 ** 16);
     // https://docs.microsoft.com/en-us/typography/opentype/spec/gsub#12-single-substitution-format-2
     case 2:
-      // eslint-disable-next-line eqeqeq
-      return table.substitute[coverageIndex] != null
-        ? table.substitute[coverageIndex]
-        : null;
+      return table.substitute[coverageIndex] ?? null;
   }
 }

addons/addon-search/src/SearchEngine.ts

@@ -198,9 +198,7 @@ export class SearchEngine {
       }
     }
 
-    if (!result) {
-      result = this._findInLine(term, searchPosition, searchOptions, isReverseSearch);
-    }
+    result ??= this._findInLine(term, searchPosition, searchOptions, isReverseSearch);
 
     // Search from startRow - 1 to top
     if (!result) {

addons/addon-serialize/src/SerializeAddon.test.ts

@@ -228,7 +228,7 @@ describe('SerializeAddon', () => {
     it('empty terminal with selection turned off', () => {
       const output = serializeAddon.serializeAsHTML();
       assert.notEqual(output, '');
-      assert.equal((output.match(/<div><span> {10}<\/span><\/div>/g) || []).length, 2);
+      assert.equal((output.match(/<div><span> {10}<\/span><\/div>/g) ?? []).length, 2);
     });
 
     it('empty terminal with no selection', () => {
@@ -245,7 +245,7 @@ describe('SerializeAddon', () => {
       const output = serializeAddon.serializeAsHTML({
         onlySelection: true
       });
-      assert.equal((output.match(/<div><span>terminal<\/span><\/div>/g) || []).length, 1, output);
+      assert.equal((output.match(/<div><span>terminal<\/span><\/div>/g) ?? []).length, 1, output);
     });
 
     it('basic terminal with html unsafe chars', async () => {
@@ -255,7 +255,7 @@ describe('SerializeAddon', () => {
       const output = serializeAddon.serializeAsHTML({
         onlySelection: true
       });
-      assert.equal((output.match(/<div><span>&lt;a>&amp;pi;<\/span><\/div>/g) || []).length, 1, output);
+      assert.equal((output.match(/<div><span>&lt;a>&amp;pi;<\/span><\/div>/g) ?? []).length, 1, output);
     });
 
     it('serializes rows within a provided range', async () => {
@@ -267,7 +267,7 @@ describe('SerializeAddon', () => {
           startCol: 4
         }
       });
-      const rowMatches = output.match(/<div><span>.*?<\/span><\/div>/g) || [];
+      const rowMatches = output.match(/<div><span>.*?<\/span><\/div>/g) ?? [];
       assert.equal(rowMatches.length, 1, output);
       assert.ok(rowMatches[0]?.includes('hello'));
       assert.ok(!output.includes('bye'));
@@ -278,56 +278,56 @@ describe('SerializeAddon', () => {
       await writeP(terminal, ' ' + sgr('1') + 'terminal' + sgr('22') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='font-weight: bold;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='font-weight: bold;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with italic styling', async () => {
       await writeP(terminal, ' ' + sgr('3') + 'terminal' + sgr('23') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='font-style: italic;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='font-style: italic;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with inverse styling', async () => {
       await writeP(terminal, ' ' + sgr('7') + 'terminal' + sgr('27') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='color: #000000; background-color: #BFBFBF;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='color: #000000; background-color: #BFBFBF;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with underline styling', async () => {
       await writeP(terminal, ' ' + sgr('4') + 'terminal' + sgr('24') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='text-decoration: underline;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='text-decoration: underline;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with double underline styling', async () => {
       await writeP(terminal, ' ' + sgr('4:2') + 'terminal' + sgr('24') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='text-decoration: underline double;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='text-decoration: underline double;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with curly underline styling', async () => {
       await writeP(terminal, ' ' + sgr('4:3') + 'terminal' + sgr('24') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='text-decoration: underline wavy;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='text-decoration: underline wavy;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with dotted underline styling', async () => {
       await writeP(terminal, ' ' + sgr('4:4') + 'terminal' + sgr('24') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='text-decoration: underline dotted;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='text-decoration: underline dotted;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with dashed underline styling', async () => {
       await writeP(terminal, ' ' + sgr('4:5') + 'terminal' + sgr('24') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='text-decoration: underline dashed;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='text-decoration: underline dashed;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with underline color (palette)', async () => {
@@ -350,49 +350,49 @@ describe('SerializeAddon', () => {
       await writeP(terminal, ' ' + sgr('8') + 'terminal' + sgr('28') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='visibility: hidden;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='visibility: hidden;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with dim styling', async () => {
       await writeP(terminal, ' ' + sgr('2') + 'terminal' + sgr('22') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='opacity: 0.5;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='opacity: 0.5;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with strikethrough styling', async () => {
       await writeP(terminal, ' ' + sgr('9') + 'terminal' + sgr('29') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='text-decoration: line-through;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='text-decoration: line-through;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with combined styling', async () => {
       await writeP(terminal, sgr('1') + ' ' + sgr('9') + 'termi' + sgr('22') + 'nal' + sgr('29') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='font-weight: bold;'> <\/span>/g) || []).length, 1, output);
-      assert.equal((output.match(/<span style='font-weight: bold; text-decoration: line-through;'>termi<\/span>/g) || []).length, 1, output);
-      assert.equal((output.match(/<span style='text-decoration: line-through;'>nal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='font-weight: bold;'> <\/span>/g) ?? []).length, 1, output);
+      assert.equal((output.match(/<span style='font-weight: bold; text-decoration: line-through;'>termi<\/span>/g) ?? []).length, 1, output);
+      assert.equal((output.match(/<span style='text-decoration: line-through;'>nal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with color styling', async () => {
       await writeP(terminal, ' ' + sgr('38;5;46') + 'terminal' + sgr('39') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='color: #00ff00;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='color: #00ff00;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with background styling', async () => {
       await writeP(terminal, ' ' + sgr('48;5;46') + 'terminal' + sgr('49') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='background-color: #00ff00;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='background-color: #00ff00;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('empty terminal with default options', async () => {
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/color: #000000; background-color: #ffffff; font-family: monospace; font-size: 15px;/g) || []).length, 1, output);
+      assert.equal((output.match(/color: #000000; background-color: #ffffff; font-family: monospace; font-size: 15px;/g) ?? []).length, 1, output);
     });
 
     it('empty terminal with custom options', async () => {
@@ -405,14 +405,14 @@ describe('SerializeAddon', () => {
       const output = serializeAddon.serializeAsHTML({
         includeGlobalBackground: true
       });
-      assert.equal((output.match(/color: #ff00ff; background-color: #00ff00; font-family: verdana; font-size: 20px;/g) || []).length, 1, output);
+      assert.equal((output.match(/color: #ff00ff; background-color: #00ff00; font-family: verdana; font-size: 20px;/g) ?? []).length, 1, output);
     });
 
     it('empty terminal with background included', async () => {
       const output = serializeAddon.serializeAsHTML({
         includeGlobalBackground: true
       });
-      assert.equal((output.match(/color: #ffffff; background-color: #000000; font-family: monospace; font-size: 15px;/g) || []).length, 1, output);
+      assert.equal((output.match(/color: #ffffff; background-color: #000000; font-family: monospace; font-size: 15px;/g) ?? []).length, 1, output);
     });
 
     it('cells with custom color styling', async () => {
@@ -422,7 +422,7 @@ describe('SerializeAddon', () => {
       await writeP(terminal, ' ' + sgr('38;5;0') + 'terminal' + sgr('39') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='color: #ffa500;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='color: #ffa500;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
 
     it('cells with color styling - xterm headless', async () => {
@@ -432,7 +432,7 @@ describe('SerializeAddon', () => {
       await writeP(terminal, ' ' + sgr('38;5;46') + 'terminal' + sgr('39') + ' ');
 
       const output = serializeAddon.serializeAsHTML();
-      assert.equal((output.match(/<span style='color: #00ff00;'>terminal<\/span>/g) || []).length, 1, output);
+      assert.equal((output.match(/<span style='color: #00ff00;'>terminal<\/span>/g) ?? []).length, 1, output);
     });
   });
 });

addons/addon-serialize/src/SerializeAddon.ts

@@ -601,7 +601,7 @@ export class SerializeAddon implements ITerminalAddon , ISerializeApi {
       throw new Error('Cannot use addon until it has been loaded');
     }
 
-    return this._serializeBufferAsHTML(this._terminal, options || {});
+    return this._serializeBufferAsHTML(this._terminal, options ?? {});
   }
 
   public dispose(): void { }

addons/addon-unicode-graphemes/src/UnicodeGraphemesAddon.ts

@@ -16,12 +16,8 @@ export class UnicodeGraphemesAddon implements ITerminalAddon , IUnicodeGraphemes
   private _oldVersion: string = '';
 
   public activate(terminal: Terminal): void {
-    if (! this._provider15) {
-      this._provider15 = new UnicodeGraphemeProvider(false);
-    }
-    if (! this._provider15Graphemes) {
-      this._provider15Graphemes = new UnicodeGraphemeProvider(true);
-    }
+    this._provider15 ??= new UnicodeGraphemeProvider(false);
+    this._provider15Graphemes ??= new UnicodeGraphemeProvider(true);
     const unicode = terminal.unicode;
     this._unicode = unicode;
     unicode.register(this._provider15);

addons/addon-web-links/src/WebLinksAddon.ts

@@ -48,7 +48,7 @@ export class WebLinksAddon implements ITerminalAddon , IWebLinksApi {
   public activate(terminal: Terminal): void {
     this._terminal = terminal;
     const options = this._options as ILinkProviderOptions;
-    const regex = options.urlRegex || strictUrlRegex;
+    const regex = options.urlRegex ?? strictUrlRegex;
     this._linkProvider = this._terminal.registerLinkProvider(new WebLinkProvider(this._terminal, regex, this._handler, options));
   }
 

addons/addon-webgl/src/TextureAtlas.ts

@@ -410,7 +410,7 @@ export class TextureAtlas implements ITextureAtlas {
     const cache = this._getContrastCache(dim);
     const adjustedColor = cache.getColor(bg, fg);
     if (adjustedColor !== undefined) {
-      return adjustedColor || undefined;
+      return adjustedColor ?? undefined;
     }
 
     const bgRgba = this._resolveBackgroundRgba(bgColorMode, bgColor, inverse);

eslint.config.mjs

@@ -66,6 +66,7 @@ export default tseslint.config(
       ],
       '@typescript-eslint/no-confusing-void-expression': ['warn', { ignoreArrowShorthand: true }],
       '@typescript-eslint/no-useless-constructor': 'warn',
+      '@typescript-eslint/prefer-nullish-coalescing': ['warn', { ignorePrimitives: true }],
       '@typescript-eslint/prefer-namespace-keyword': 'warn',
       '@typescript-eslint/no-unused-vars': ['warn', { vars: 'all', args: 'none' }],
       '@typescript-eslint/no-require-imports': 'off',
@@ -140,5 +141,12 @@ export default tseslint.config(
       '@typescript-eslint/explicit-function-return-type': 'off',
       '@typescript-eslint/explicit-member-accessibility': 'off'
     }
+  },
+  {
+    // Disable prefer-nullish-coalescing for files without strictNullChecks
+    files: ['demo/**/*.ts', '**/*.benchmark.ts'],
+    rules: {
+      '@typescript-eslint/prefer-nullish-coalescing': 'off'
+    }
   }
 );

src/browser/CoreBrowserTerminal.ts

@@ -793,15 +793,15 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
       if (!(events & CoreMouseEventType.UP)) {
         this._document!.removeEventListener('mouseup', requestedEvents.mouseup!);
         requestedEvents.mouseup = null;
-      } else if (!requestedEvents.mouseup) {
-        requestedEvents.mouseup = eventListeners.mouseup;
+      } else {
+        requestedEvents.mouseup ??= eventListeners.mouseup;
       }
 
       if (!(events & CoreMouseEventType.DRAG)) {
         this._document!.removeEventListener('mousemove', requestedEvents.mousedrag!);
         requestedEvents.mousedrag = null;
-      } else if (!requestedEvents.mousedrag) {
-        requestedEvents.mousedrag = eventListeners.mousedrag;
+      } else {
+        requestedEvents.mousedrag ??= eventListeners.mousedrag;
       }
     }));
     // force initial onProtocolChange so we dont miss early mouse requests

src/browser/RenderDebouncer.ts

@@ -40,8 +40,8 @@ export class RenderDebouncer implements IRenderDebouncerWithCallback {
   public refresh(rowStart: number | undefined, rowEnd: number | undefined, rowCount: number): void {
     this._rowCount = rowCount;
     // Get the min/max row start/end for the arg values
-    rowStart = rowStart !== undefined ? rowStart : 0;
-    rowEnd = rowEnd !== undefined ? rowEnd : this._rowCount - 1;
+    rowStart = rowStart ?? 0;
+    rowEnd = rowEnd ?? this._rowCount - 1;
     // Set the properties to the updated values
     this._rowStart = this._rowStart !== undefined ? Math.min(this._rowStart, rowStart) : rowStart;
     this._rowEnd = this._rowEnd !== undefined ? Math.max(this._rowEnd, rowEnd) : rowEnd;

src/browser/TimeBasedDebouncer.ts

@@ -37,8 +37,8 @@ export class TimeBasedDebouncer implements IRenderDebouncer {
   public refresh(rowStart: number | undefined, rowEnd: number | undefined, rowCount: number): void {
     this._rowCount = rowCount;
     // Get the min/max row start/end for the arg values
-    rowStart = rowStart !== undefined ? rowStart : 0;
-    rowEnd = rowEnd !== undefined ? rowEnd : this._rowCount - 1;
+    rowStart = rowStart ?? 0;
+    rowEnd = rowEnd ?? this._rowCount - 1;
     // Set the properties to the updated values
     this._rowStart = this._rowStart !== undefined ? Math.min(this._rowStart, rowStart) : rowStart;
     this._rowEnd = this._rowEnd !== undefined ? Math.max(this._rowEnd, rowEnd) : rowEnd;

src/browser/public/Terminal.ts

@@ -84,10 +84,7 @@ export class Terminal extends Disposable implements ITerminalApi {
 
   public get element(): HTMLElement | undefined { return this._core.element; }
   public get parser(): IParser {
-    if (!this._parser) {
-      this._parser = new ParserApi(this._core);
-    }
-    return this._parser;
+    return this._parser ??= new ParserApi(this._core);
   }
   public get unicode(): IUnicodeHandling {
     this._checkProposedApi();
@@ -97,10 +94,7 @@ export class Terminal extends Disposable implements ITerminalApi {
   public get rows(): number { return this._core.rows; }
   public get cols(): number { return this._core.cols; }
   public get buffer(): IBufferNamespaceApi {
-    if (!this._buffer) {
-      this._buffer = this._register(new BufferNamespaceApi(this._core));
-    }
-    return this._buffer;
+    return this._buffer ??= this._register(new BufferNamespaceApi(this._core));
   }
   public get markers(): ReadonlyArray<IMarker> {
     return this._core.markers;

src/browser/renderer/dom/DomRendererRowFactory.ts

@@ -494,8 +494,8 @@ export class DomRendererRowFactory {
       // Dim cells only require half the contrast, otherwise they wouldn't be distinguishable from
       // non-dim cells
       const ratio = this._optionsService.rawOptions.minimumContrastRatio / (cell.isDim() ? 2 : 1);
-      adjustedColor = color.ensureContrastRatio(bgOverride || bg, fgOverride || fg, ratio);
-      cache.setColor((bgOverride || bg).rgba, (fgOverride || fg).rgba, adjustedColor ?? null);
+      adjustedColor = color.ensureContrastRatio(bgOverride ?? bg, fgOverride ?? fg, ratio);
+      cache.setColor((bgOverride ?? bg).rgba, (fgOverride ?? fg).rgba, adjustedColor ?? null);
     }
 
     if (adjustedColor) {

src/browser/services/RenderService.ts

@@ -347,13 +347,11 @@ class SynchronizedOutputHandler {
       this._end = Math.max(this._end, end);
     }
 
-    if (this._timeout === undefined) {
-      this._timeout = this._coreBrowserService.window.setTimeout(() => {
-        this._timeout = undefined;
-        this._coreService.decPrivateModes.synchronizedOutput = false;
-        this._onTimeout();
-      }, Constants.SYNCHRONIZED_OUTPUT_TIMEOUT_MS);
-    }
+    this._timeout ??= this._coreBrowserService.window.setTimeout(() => {
+      this._timeout = undefined;
+      this._coreService.decPrivateModes.synchronizedOutput = false;
+      this._onTimeout();
+    }, Constants.SYNCHRONIZED_OUTPUT_TIMEOUT_MS);
   }
 
   public flush(): { start: number, end: number } | undefined {