Introduce interface ThumbnailGenerationLogFileContent.

src-shared/thumbnail/cache/thumbnail-cache-util.ts

@@ -80,15 +80,18 @@ export function getOriginalFilePath(thumbnailFilePath: string): string {
   return originalFilePath;
 }
 
-const lastModifiedKey = 'LastModified';
-const isThumbnailFileCreatedKey = 'IsThumbnailFileCreated';
+interface ThumbnailGenerationLogFileContent {
+  LastModified: string;
+  IsThumbnailFileCreated: boolean;
+}
 
 export async function createThumbnailGenerationLogFile(srcFilePath: string, thumbnailFileDir: string, isThumbnailFileCreated: boolean, logger: PrependedLogger) {
   const srcFileName = pathModule.basename(srcFilePath);
   const lastModified = fsExtra.statSync(srcFilePath).mtime.toISOString();
-  const fileContentObj = {};
-  fileContentObj[lastModifiedKey] = lastModified;
-  fileContentObj[isThumbnailFileCreatedKey] = isThumbnailFileCreated;
+  const fileContentObj: ThumbnailGenerationLogFileContent = {
+    LastModified: lastModified,
+    IsThumbnailFileCreated: isThumbnailFileCreated
+  };
   const fileContentStr = JSON.stringify(fileContentObj, null, 2);
   const logFilePath = pathModule.join(thumbnailFileDir, `${srcFileName}.log.json`);
 
@@ -138,15 +141,15 @@ export function lastModifiedMatchBetweenSrcFileAndThumbnailGenerationLogFile(src
     return false;
   }
 
-  let fileContentObj;
+  let fileContentObj: ThumbnailGenerationLogFileContent;
   try {
     fileContentObj = JSON.parse(fileContentStr);
   } catch (error) {
     Logger.warn(`Failed to parse the content of the log file "${logFilePath}" as JSON format. The log file is for thumbnail generation result of "${srcFilePath}". error: ${error}`, error);
     return false;
   }
 
-  const lastModifiedFromLogFile = fileContentObj[lastModifiedKey];
+  const lastModifiedFromLogFile = fileContentObj.LastModified;
   if (!lastModifiedFromLogFile)
     return false;