diff --git a/src/core/annotation.js b/src/core/annotation.js
index d6b612b14..a1a7a76a6 100644
--- a/src/core/annotation.js
+++ b/src/core/annotation.js
@@ -3488,8 +3488,8 @@ class ChoiceWidgetAnnotation extends WidgetAnnotation {
       // always make the field value an array with zero, one or multiple items.
       if (typeof this.data.fieldValue === "string") {
         this.data.fieldValue = [this.data.fieldValue];
-      } else if (!this.data.fieldValue) {
-        this.data.fieldValue = [];
+      } else {
+        this.data.fieldValue ||= [];
       }
     } else {
       // The specs say that we should have an indices array only with
diff --git a/src/core/catalog.js b/src/core/catalog.js
index 8c07a2f3f..ee5484e26 100644
--- a/src/core/catalog.js
+++ b/src/core/catalog.js
@@ -998,9 +998,7 @@ class Catalog {
         warn(`Bad value, for key "${key}", in ViewerPreferences: ${value}.`);
         continue;
       }
-      if (!prefs) {
-        prefs = Object.create(null);
-      }
+      prefs ??= Object.create(null);
       prefs[key] = prefValue;
     }
     return shadow(this, "viewerPreferences", prefs);
@@ -1042,9 +1040,7 @@ class Catalog {
       const nameTree = new NameTree(obj.getRaw("EmbeddedFiles"), this.xref);
       for (const [key, value] of nameTree.getAll()) {
         const fs = new FileSpec(value, this.xref);
-        if (!attachments) {
-          attachments = Object.create(null);
-        }
+        attachments ??= Object.create(null);
         attachments[stringToPDFString(key)] = fs.serializable;
       }
     }
@@ -1058,9 +1054,7 @@ class Catalog {
     if (obj instanceof Dict && obj.has("XFAImages")) {
       const nameTree = new NameTree(obj.getRaw("XFAImages"), this.xref);
       for (const [key, value] of nameTree.getAll()) {
-        if (!xfaImages) {
-          xfaImages = new Dict(this.xref);
-        }
+        xfaImages ??= new Dict(this.xref);
         xfaImages.set(stringToPDFString(key), value);
       }
     }
diff --git a/src/core/document.js b/src/core/document.js
index 7f91414cd..b1e1caaec 100644
--- a/src/core/document.js
+++ b/src/core/document.js
@@ -1532,9 +1532,7 @@ class PDFDocument {
             warn(`Bad value, for custom key "${key}", in Info: ${value}.`);
             continue;
           }
-          if (!docInfo.Custom) {
-            docInfo.Custom = Object.create(null);
-          }
+          docInfo.Custom ??= Object.create(null);
           docInfo.Custom[key] = customValue;
           continue;
       }
diff --git a/src/core/xfa/parser.js b/src/core/xfa/parser.js
index 8b6bdd699..4f506fb24 100644
--- a/src/core/xfa/parser.js
+++ b/src/core/xfa/parser.js
@@ -91,9 +91,7 @@ class XFAParser extends XMLParserBase {
         }
       } else if (name.startsWith("xmlns:")) {
         const prefix = name.substring("xmlns:".length);
-        if (!prefixes) {
-          prefixes = [];
-        }
+        prefixes ??= [];
         prefixes.push({ prefix, value });
       } else {
         const i = name.indexOf(":");
@@ -102,10 +100,7 @@ class XFAParser extends XMLParserBase {
         } else {
           // Attributes can have their own namespace.
           // For example in data, we can have <foo xfa:dataNode="dataGroup"/>
-          let nsAttrs = attributeObj[$nsAttributes];
-          if (!nsAttrs) {
-            nsAttrs = attributeObj[$nsAttributes] = Object.create(null);
-          }
+          const nsAttrs = (attributeObj[$nsAttributes] ??= Object.create(null));
           const [ns, attrName] = [name.slice(0, i), name.slice(i + 1)];
           const attrs = (nsAttrs[ns] ||= Object.create(null));
           attrs[attrName] = value;
diff --git a/src/core/xfa/template.js b/src/core/xfa/template.js
index 594ab25a7..46cbffb1c 100644
--- a/src/core/xfa/template.js
+++ b/src/core/xfa/template.js
@@ -2462,9 +2462,7 @@ class ExclGroup extends XFAObject {
 
     setAccess(this, attributes.class);
 
-    if (!this[$extra]) {
-      this[$extra] = Object.create(null);
-    }
+    this[$extra] ||= Object.create(null);
 
     Object.assign(this[$extra], {
       children,
@@ -2953,9 +2951,7 @@ class Field extends XFAObject {
       }
     }
 
-    if (!ui.attributes.style) {
-      ui.attributes.style = Object.create(null);
-    }
+    ui.attributes.style ||= Object.create(null);
 
     let aElement = null;
 
@@ -3048,9 +3044,7 @@ class Field extends XFAObject {
       caption.attributes.class[0] = "xfaCaptionForCheckButton";
     }
 
-    if (!ui.attributes.class) {
-      ui.attributes.class = [];
-    }
+    ui.attributes.class ||= [];
 
     ui.children.splice(0, 0, caption);
 
@@ -4067,11 +4061,9 @@ class PageArea extends XFAObject {
   }
 
   [$getNextPage]() {
-    if (!this[$extra]) {
-      this[$extra] = {
-        numberOfUse: 0,
-      };
-    }
+    this[$extra] ||= {
+      numberOfUse: 0,
+    };
 
     const parent = this[$getParent]();
     if (parent.relation === "orderedOccurrence") {
@@ -4090,11 +4082,9 @@ class PageArea extends XFAObject {
 
   [$toHTML]() {
     // TODO: incomplete.
-    if (!this[$extra]) {
-      this[$extra] = {
-        numberOfUse: 1,
-      };
-    }
+    this[$extra] ||= {
+      numberOfUse: 1,
+    };
 
     const children = [];
     this[$extra].children = children;
@@ -4186,13 +4176,11 @@ class PageSet extends XFAObject {
   }
 
   [$getNextPage]() {
-    if (!this[$extra]) {
-      this[$extra] = {
-        numberOfUse: 1,
-        pageIndex: -1,
-        pageSetIndex: -1,
-      };
-    }
+    this[$extra] ||= {
+      numberOfUse: 1,
+      pageIndex: -1,
+      pageSetIndex: -1,
+    };
 
     if (this.relation === "orderedOccurrence") {
       if (this[$extra].pageIndex + 1 < this.pageArea.children.length) {
@@ -5067,9 +5055,7 @@ class Subform extends XFAObject {
 
     setAccess(this, attributes.class);
 
-    if (!this[$extra]) {
-      this[$extra] = Object.create(null);
-    }
+    this[$extra] ||= Object.create(null);
 
     Object.assign(this[$extra], {
       children,
@@ -5495,9 +5481,7 @@ class Template extends XFAObject {
       }
     }
 
-    if (!pageArea) {
-      pageArea = pageAreas[0];
-    }
+    pageArea ||= pageAreas[0];
 
     pageArea[$extra] = {
       numberOfUse: 1,
diff --git a/src/scripting_api/app.js b/src/scripting_api/app.js
index 74dba793d..978025936 100644
--- a/src/scripting_api/app.js
+++ b/src/scripting_api/app.js
@@ -202,18 +202,15 @@ class App extends PDFObject {
   }
 
   get constants() {
-    if (!this._constants) {
-      this._constants = Object.freeze({
-        align: Object.freeze({
-          left: 0,
-          center: 1,
-          right: 2,
-          top: 3,
-          bottom: 4,
-        }),
-      });
-    }
-    return this._constants;
+    return (this._constants ??= Object.freeze({
+      align: Object.freeze({
+        left: 0,
+        center: 1,
+        right: 2,
+        top: 3,
+        bottom: 4,
+      }),
+    }));
   }
 
   set constants(_) {