diff --git a/js/components/document-controls.js b/js/components/document-controls.js
index 4d613b6..4834d25 100644
--- a/js/components/document-controls.js
+++ b/js/components/document-controls.js
@@ -218,7 +218,6 @@ class DocumentControls {
         if (status && this.controlPanel) {
             const title = this.controlPanel.querySelector('div');
             if (title) {
-                const statusText = `Document Controls (${status.totalSections} sections, ${status.editingSections} editing)`;
                 // Could update title or add status indicator
             }
         }
diff --git a/js/components/dom-renderer.js b/js/components/dom-renderer.js
index 8e4a0bf..0069fcb 100644
--- a/js/components/dom-renderer.js
+++ b/js/components/dom-renderer.js
@@ -1068,7 +1068,7 @@ class DOMRenderer {
         };
 
         this.eventHistory.push(eventRecord);
-        if (this.eventStats.hasOwnProperty(eventType)) {
+        if (Object.prototype.hasOwnProperty.call(this.eventStats, eventType)) {
             this.eventStats[eventType]++;
         }
 
diff --git a/js/controls/control-base.js b/js/controls/control-base.js
index 2bd764b..6524d7d 100644
--- a/js/controls/control-base.js
+++ b/js/controls/control-base.js
@@ -461,7 +461,6 @@ class ControlBase {
         };
 
         // Store current computed position before clearing styles
-        const computedStyle = window.getComputedStyle(this.element);
         const currentLeft = rect.left;
         const currentTop = rect.top;
 
@@ -676,8 +675,6 @@ class ControlBase {
             // Measure content size by temporarily allowing natural sizing
             const originalOverflow = contentBody.style.overflow;
             const originalMaxHeight = panel.style.maxHeight;
-            const originalHeight = panel.style.height;
-            const originalWidth = panel.style.width;
 
             // Temporarily remove constraints to measure natural size
             contentBody.style.overflow = 'visible';
@@ -686,6 +683,7 @@ class ControlBase {
             panel.style.width = 'auto';
 
             // Force reflow and measure
+            // eslint-disable-next-line no-unused-expressions
             panel.offsetHeight; // Force reflow
             const contentRect = contentBody.getBoundingClientRect();
             const headerHeight = this.element.querySelector('.control-header')?.offsetHeight || 24;
diff --git a/js/controls/debug-control.js b/js/controls/debug-control.js
index eb8acaa..27cd685 100644
--- a/js/controls/debug-control.js
+++ b/js/controls/debug-control.js
@@ -190,7 +190,6 @@ class DebugControl extends ControlBase {
     generatePerformanceHTML() {
         return this.safeOperation(() => {
             const timing = performance.timing;
-            const navigation = performance.getEntriesByType('navigation')[0];
 
             const metrics = {
                 pageLoad: timing.loadEventEnd - timing.navigationStart,
diff --git a/js/controls/edit-control.js b/js/controls/edit-control.js
index 65d3d86..bcd2d08 100644
--- a/js/controls/edit-control.js
+++ b/js/controls/edit-control.js
@@ -419,9 +419,10 @@ class EditControl extends ControlBase {
             );
 
             const textNodes = [];
-            let node;
-            while (node = walker.nextNode()) {
+            let node = walker.nextNode();
+            while (node) {
                 textNodes.push(node);
+                node = walker.nextNode();
             }
 
             textNodes.forEach(textNode => {
diff --git a/js/main.js b/js/main.js
index 7ab7dc1..f362c1c 100644
--- a/js/main.js
+++ b/js/main.js
@@ -71,6 +71,7 @@ const MarkitectMain = {
                 return null;
             }
 
+            // eslint-disable-next-line new-cap
             const controlInstance = new controlClass();
             if (!controlInstance || typeof controlInstance.createControl !== 'function') {
                 throw new Error(`Invalid ${controlName} instance`);
diff --git a/js/tests/button-events.test.js b/js/tests/button-events.test.js
index bf66f3d..1c12257 100644
--- a/js/tests/button-events.test.js
+++ b/js/tests/button-events.test.js
@@ -91,24 +91,9 @@ describe('Button Functionality and DOM Events', () => {
     });
 
     describe('Button event propagation', () => {
-        test('should prevent event bubbling for section buttons', () => {
-            const editBtn = document.querySelector('.edit-btn');
-            let sectionClicked = false;
-
-            mockSection.addEventListener('click', () => {
-                sectionClicked = true;
-            });
-
-            // Create event with stopPropagation mock
-            const clickEvent = new Event('click', { bubbles: true });
-            clickEvent.stopPropagation = jest.fn();
-
-            editBtn.dispatchEvent(clickEvent);
-
-            // In real implementation, should call stopPropagation
-            expect(clickEvent.stopPropagation).toHaveBeenCalledWith ||
-        expect(sectionClicked).toBe(false);
-        });
+        // Was vacuous (`expect(fn).toHaveBeenCalledWith || expect(...)` never ran an assertion) and
+        // false once made real: the mock buttons here have no handler. Needs the real DOMRenderer wired in.
+        test.todo('should prevent event bubbling for section buttons');
 
         test('should handle rapid button clicks gracefully', () => {
             const editBtn = document.querySelector('.edit-btn');
diff --git a/js/widgets/base/UIWidget.js b/js/widgets/base/UIWidget.js
index 0133b33..067688a 100644
--- a/js/widgets/base/UIWidget.js
+++ b/js/widgets/base/UIWidget.js
@@ -96,6 +96,7 @@ export class UIWidget extends Widget {
             this.element.style.display = '';
 
             // Force reflow
+            // eslint-disable-next-line no-unused-expressions
             this.element.offsetHeight;
 
             this.element.style.opacity = '1';
diff --git a/js/widgets/navigation/DocumentNavigator.js b/js/widgets/navigation/DocumentNavigator.js
index 742ed3c..f36ad4a 100644
--- a/js/widgets/navigation/DocumentNavigator.js
+++ b/js/widgets/navigation/DocumentNavigator.js
@@ -404,6 +404,7 @@ export class DocumentNavigator extends UIWidget {
             this.navigationList.style.transition = `opacity ${this.animationDuration}ms ease-in-out`;
 
             // Force reflow
+            // eslint-disable-next-line no-unused-expressions
             this.element.offsetWidth;
 
             this.element.style.width = this.config.width;
diff --git a/package.json b/package.json
index 4d8f374..9620979 100644
--- a/package.json
+++ b/package.json
@@ -184,6 +184,18 @@
       "StatusControl": "readonly",
       "DebugControl": "readonly",
       "EditControl": "readonly"
-    }
+    },
+    "overrides": [
+      {
+        "files": [
+          "**/*.test.js",
+          "js/tests/**/*.js"
+        ],
+        "rules": {
+          "jest/no-conditional-expect": "warn",
+          "no-unused-vars": "warn"
+        }
+      }
+    ]
   }
 }
diff --git a/src/components/ui-edit-button/ui-edit-button.test.js b/src/components/ui-edit-button/ui-edit-button.test.js
index 1df6d91..7ac81e7 100644
--- a/src/components/ui-edit-button/ui-edit-button.test.js
+++ b/src/components/ui-edit-button/ui-edit-button.test.js
@@ -5,8 +5,8 @@ describe('<ui-edit-button>', () => {
         const el = document.createElement('ui-edit-button');
         document.body.appendChild(el);
         const button = el.shadowRoot.querySelector('button');
-        expect(button).to.exist;
-        expect(button.textContent).to.include('Edit');
+        expect(button).toBeTruthy();
+        expect(button.textContent).toContain('Edit');
     });
 
     it('triggers a click handler', () => {
@@ -19,6 +19,6 @@ describe('<ui-edit-button>', () => {
         const button = el.shadowRoot.querySelector('button');
         button.click();
 
-        expect(clicked).to.be.true;
+        expect(clicked).toBe(true);
     });
 });