1 files changed, 20 insertions, 6 deletions

diff --git a/src/offscreen/ocr/index.js b/src/offscreen/ocr/index.js
index 432811e..dfe93c9 100644
--- a/src/offscreen/ocr/index.js
+++ b/src/offscreen/ocr/index.js
@@ -1,20 +1,29 @@
-import Tesseract from "./tesseract.esm.min.js";
+import Tesseract from "./static/tesseract.esm.min.js";
 
 let ocrWorker = null;
 const WORKER_PATH = chrome.runtime.getURL("offscreen/ocr/static/worker.min.js");
 const CORE_PATH = chrome.runtime.getURL("offscreen/ocr/static");
 
+/**
+ * Creates (or reuses) a Tesseract.js worker and recognises text from
+ * the given image data URL.  The worker is configured to only recognise
+ * uppercase alphanumerics (excluding `0`, `O`, `1`, `I`) suitable for
+ * CAPTCHA text.
+ *
+ * @param {string} dataURL - A `data:image/png;base64,…` string.
+ * @returns {{ text: string, confidence: number }}
+ */
 async function performOcrInOffscreen(dataURL) {
 	if (!ocrWorker) {
 		ocrWorker = await Tesseract.createWorker("eng", 1, {
 			workerPath: WORKER_PATH,
 			corePath: CORE_PATH,
-			workerBlobURL: false,
+			workerBlobURL: false
 		});
 
 		await ocrWorker.setParameters({
 			// The only characters that appears
-			tessedit_char_whitelist: "ABCDEFGHJKLMNPQRSTUVWXYZ23456789",
+			tessedit_char_whitelist: "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"
 		});
 	}
 
@@ -23,13 +32,18 @@ async function performOcrInOffscreen(dataURL) {
 }
 
 // Listen for messages from the Service Worker
-chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
+/**
+ * Handles two message types from the background service worker:
+ * - `"OFFSCREEN_OCR_REQUEST"`: runs OCR on the supplied data URL.
+ * - `"OFFSCREEN_TERMINATE_OCR_WORKER"`: terminates the worker to free memory.
+ */
+chrome.runtime.onMessage.addListener((message, _sender, sendResponse) => {
 	if (message.type === "OFFSCREEN_OCR_REQUEST" && message.dataURL) {
 		performOcrInOffscreen(message.dataURL)
-			.then(({ text, confidence }) => {
+			.then(function({ text, confidence }) {
 				sendResponse({ success: true, text, confidence });
 			})
-			.catch(error => {
+			.catch(function(error) {
 				sendResponse({ success: false, error: error.message });
 			});
 		return true;