refactoring

scripts/background/messaging.js

@@ -0,0 +1,50 @@
+
+/**
+ * Repeatedly sending a message to target tab until the response is detected good.
+ * @param {object} tab the table where to send the message
+ * @param {object} req the request data.
+ * @param {function} cond success condition function, r:any=>boolean
+ * @param {number} interval interval for detecting
+ * @param {string} log messages logged to console.
+ * @return {Promise} a promise of the response.
+ */
+function sendMessage(tab, req, log, cond, interval) {
+    interval = interval || 500;
+    return new Promise((resolve, reject) => {
+
+        loop();
+
+        async function loop() {
+            // console.log("request for", req.action);
+            let tabAvailable = await getTabByID(tab.id);
+            if (!tabAvailable) {
+                reject("Task interrupted due to the target tab is closed.");
+                return;
+            }
+
+            chrome.tabs.sendMessage(tab.id, req, r => {
+                if (chrome.runtime.lastError) {
+                    reject(chrome.runtime.lastError.message);
+                    return;
+                }
+                let flag = !cond || cond(r);
+                if (log) console.log(log, flag ? '(OK)' : '(failed)');
+                if (flag) {
+                    resolve(r);
+                } else {
+                    setTimeout(() => {
+                        loop();
+                    }, interval);
+                }
+            });
+        }
+    });
+}
+
+chrome.runtime.onMessage.addListener(function (message, sender, sendResponse) {
+    if (!message.action || !message.action.startsWith(EXT_NAME)) {
+        return;
+    }
+    sendResponse("Calling from user pages is not allowed.");
+    return;
+});