refactor: improve performance and validation in accessibility tests and type guards

Co-authored-by: tsmarvin <[email protected]>

Author: Copilot

src/scripts/index.ts

@@ -1265,17 +1265,38 @@ const processedTimezoneCache = new Map<number, ProcessedTimezoneData>();
 // Cache key for localStorage
 const TIMEZONE_CACHE_KEY = 'everytimezone_processed_timezones';
 
+/**
+ * Type guard to check if an object is a valid TimeZone
+ */
+function isValidTimeZone(obj: unknown): obj is TimeZone {
+  return (
+    typeof obj === 'object' &&
+    obj !== null &&
+    typeof (obj as TimeZone).name === 'string' &&
+    typeof (obj as TimeZone).offset === 'number' &&
+    typeof (obj as TimeZone).displayName === 'string' &&
+    typeof (obj as TimeZone).iana === 'string' &&
+    typeof (obj as TimeZone).cityName === 'string' &&
+    typeof (obj as TimeZone).abbreviation === 'string'
+    // Note: daylight, isCustom, isOffCycle, coordinates are optional properties
+  );
+}
+
 /**
  * Type guard to check if an object is a valid ProcessedTimezoneData
  */
 function isProcessedTimezoneData(obj: unknown): obj is ProcessedTimezoneData {
+  const candidate = obj as ProcessedTimezoneData;
   return (
     typeof obj === 'object' &&
     obj !== null &&
-    Array.isArray((obj as ProcessedTimezoneData).juneTimeZones) &&
-    Array.isArray((obj as ProcessedTimezoneData).decemberTimeZones) &&
-    typeof (obj as ProcessedTimezoneData).userTimezone === 'string' &&
-    typeof (obj as ProcessedTimezoneData).currentYear === 'number'
+    Array.isArray(candidate.juneTimeZones) &&
+    Array.isArray(candidate.decemberTimeZones) &&
+    typeof candidate.userTimezone === 'string' &&
+    typeof candidate.currentYear === 'number' &&
+    // Validate that array contents are valid TimeZone objects to prevent runtime errors
+    candidate.juneTimeZones.every(isValidTimeZone) &&
+    candidate.decemberTimeZones.every(isValidTimeZone)
   );
 }
 

test/accessibility-comprehensive.test.ts

@@ -293,15 +293,15 @@ describe('WCAG AAA Accessibility Standards', () => {
               it('should meet WCAG AAA color contrast requirements (7:1 for normal text)', () => {
                 // Test all text elements for complete accessibility coverage
                 const textElements = document.querySelectorAll('*');
-                let contrastIssues: string[] = [];
-
-                textElements.forEach((element, index) => {
+                
+                // Use functional approach for better performance instead of repeatedly calling push()
+                const contrastIssues = Array.from(textElements).flatMap((element, index) => {
                   const styles = window.getComputedStyle(element);
                   const textColor = styles.color;
                   const backgroundColor = getComputedBackgroundColor(element);
 
                   // Test all elements including hidden ones for screen reader compatibility
-                  if (!element.textContent?.trim()) return;
+                  if (!element.textContent?.trim()) return [];
 
                   if (textColor && backgroundColor) {
                     const textRGB = parseColor(textColor);
@@ -311,12 +311,11 @@ describe('WCAG AAA Accessibility Standards', () => {
                       const contrastRatio = getContrastRatio(textRGB, bgRGB);
                       // WCAG AAA requires 7:1 for normal text (not 4.5:1 which is AA)
                       if (contrastRatio < 7.0) {
-                        contrastIssues.push(
-                          `${element.tagName}[${index}] "${element.textContent?.trim().substring(0, 20)}..." contrast ratio ${contrastRatio.toFixed(2)}:1 is below WCAG AAA standard (7:1)`
-                        );
+                        return [`${element.tagName}[${index}] "${element.textContent?.trim().substring(0, 20)}..." contrast ratio ${contrastRatio.toFixed(2)}:1 is below WCAG AAA standard (7:1)`];
                       }
                     }
                   }
+                  return [];
                 });
 
                 expect(contrastIssues.length, `Contrast issues found at ${size.name}: ${contrastIssues.join(', ')}`).toBe(0);
@@ -325,15 +324,15 @@ describe('WCAG AAA Accessibility Standards', () => {
               it('should meet WCAG AAA large text contrast requirements (4.5:1)', () => {
                 // Test all elements for complete accessibility coverage
                 const allElements = document.querySelectorAll('*');
-                let contrastIssues: string[] = [];
-
-                allElements.forEach((element, index) => {
+                
+                // Use functional approach for better performance instead of repeatedly calling push()
+                const contrastIssues = Array.from(allElements).flatMap((element, index) => {
                   const styles = window.getComputedStyle(element);
                   const fontSize = parseFloat(styles.fontSize);
                   const fontWeight = styles.fontWeight;
 
                   // Test all elements including hidden ones for screen reader compatibility  
-                  if (!element.textContent?.trim()) return;
+                  if (!element.textContent?.trim()) return [];
 
                   // Large text is 18pt+ (24px+) or 14pt+ (18.5px+) bold according to WCAG
                   const isLargeText = fontSize >= 24 || (fontSize >= 18.5 && (fontWeight === 'bold' || parseInt(fontWeight) >= 700));
@@ -350,13 +349,12 @@ describe('WCAG AAA Accessibility Standards', () => {
                         const contrastRatio = getContrastRatio(textRGB, bgRGB);
                         // WCAG AAA requires 4.5:1 for large text
                         if (contrastRatio < 4.5) {
-                          contrastIssues.push(
-                            `Large text ${element.tagName}[${index}] "${element.textContent?.trim().substring(0, 20)}..." contrast ratio ${contrastRatio.toFixed(2)}:1 is below WCAG AAA standard (4.5:1)`
-                          );
+                          return [`Large text ${element.tagName}[${index}] "${element.textContent?.trim().substring(0, 20)}..." contrast ratio ${contrastRatio.toFixed(2)}:1 is below WCAG AAA standard (4.5:1)`];
                         }
                       }
                     }
                   }
+                  return [];
                 });
 
                 expect(contrastIssues.length, `Large text contrast issues at ${size.name}: ${contrastIssues.join(', ')}`).toBe(0);