code optimize (sendMessageAndDetect)

scripts/background.js

@@ -1,6 +1,9 @@
 chrome.runtime.onMessage.addListener(function (message, sender, sendResponse) {
     if (message.from === "doExtractRequest")
         extract(...message.args).catch(
-            err => console.log(err)
+            err => {
+                console.log(err);
+                alert(err);
+            }
         );
 });

scripts/extract.js

@@ -27,13 +27,13 @@ function extract(itemsSelector, fieldSelectors, url, ...args) {
                     results => {
                         data.push(...results);
                         return redirectTab(tab, url).then(
-                            tab => extractTabData(tab, itemsSelector, fieldSelectors)
+                            () => extractData(tab, itemsSelector, fieldSelectors)
                         );
                     },
                     () => p
                 ), Promise.resolve([]));
             } else {
-                pms = extractTabData(tab, itemsSelector, fieldSelectors);
+                pms = extractData(tab, itemsSelector, fieldSelectors);
             }
             pms.then(
                 results => {
@@ -48,108 +48,84 @@ function extract(itemsSelector, fieldSelectors, url, ...args) {
     });
 }
 
-function extractTabData(tab, itemsSelector, fieldSelectors) {
+function redirectTab(tab, url) {
-    let done = false;
+    let curUrl = "";
-    return new Promise((resolve, reject) => {
+    return queryUrl(tab)
-        chrome.tabs.sendMessage(
+        .then(u => {
-            tab.id, {
+            if (url !== u) {
-                from: "doExtractRequest",
+                curUrl = u;
-                itemsSelector: itemsSelector,
+                let req = {
-                fieldSelectors: fieldSelectors
+                    from: "doExtractGotoUrl",
-            },
+                    url: url
-            response => {
+                }
-                done = true;
+                chrome.tabs.sendMessage(tab.id, req);
-                resolve(response);
             }
-        );
+        })
-        setTimeout(() => {
+        .then(() => queryUrl(tab, curUrl))
-            if (!done) reject(`extractTabData failed after 2 second.`);
+        .then(() => reportIn(tab));
-        }, 2000);
-    });
 }
 
-function redirectTab(tab, url) {
+function extractData(tab, itemsSelector, fieldSelectors) {
-    return new Promise((resolve, reject) => {
+    let req = {
-        let req = {
+        from: "doExtractRequest",
-            from: "doExtractGotoUrl",
+        itemsSelector: itemsSelector,
-            url: url
+        fieldSelectors: fieldSelectors
-        }
+    }
-        let curUrl = "";
+    let failMsg = "extractTabData failed after 10 second.";
-        queryUrl(tab)
+    let cond = r => !!r;
-            .then(u => {
+    return sendMessageAndDetect(tab, req, cond, failMsg);
-                if (url !== u) {
-                    curUrl = u;
-                    chrome.tabs.sendMessage(tab.id, req);
-                }
-            })
-            .then(() => queryUrl(tab, curUrl))
-            .then(() => reportIn(tab))
-            .then(tab => resolve(tab))
-            .catch(err => reject(err));
-    });
 }
 
 function reportIn(tab) {
     let req = {
         from: "doExtractReportIn"
     }
-    return new Promise((resolve, reject) => {
+    let failMsg = "reportIn failed after 10 second.";
-        let timeOut;
+    let cond = r => r == req.from;
-        let rejectTimeout = setTimeout(() => {
+    return sendMessageAndDetect(tab, req, cond, failMsg);
-            reject(`reportIn failed after 10 second.`);
-            clearTimeout(timeOut);
-        }, 10000);
-        loop();
-
-        function loop() {
-            chrome.tabs.sendMessage(tab.id, req, r => {
-                if (r == req.from) {
-                    resolve(tab);
-                    clearTimeout(rejectTimeout);
-                } else {
-                    timeOut = setTimeout(() => {
-                        loop();
-                    }, 500);
-                }
-            });
-        }
-    });
 }
 
 function queryUrl(tab, urlExcluded) {
     let req = {
         from: "doExtractQueryUrl"
     }
+    let failMsg = "queryUrl failed after 10 second.";
+    let cond = url => url && (!urlExcluded || (urlExcluded && urlExcluded != url));
+    return sendMessageAndDetect(tab, req, cond, failMsg);
+}
+
+/**
+ * Repeatedly sending a message to target tab until the response is detected good.
+ * The response is returned with the Promise.
+ * @param {chrome.tab} tab the table where to send the message
+ * @param {object} req the request data.
+ * @param {function} cond success condition function, r:any=>boolean
+ * @param {string} failMsg message when failed after time out
+ * @param {number} failedTimeOut fail time out
+ * @param {number} detectInterval interval for detecting
+ */
+function sendMessageAndDetect(tab, req, cond, failMsg, failedTimeOut, detectInterval) {
+    failedTimeOut = failedTimeOut || 10000;
+    detectInterval = detectInterval || 500;
     return new Promise((resolve, reject) => {
         let timeOut;
         let rejectTimeout = setTimeout(() => {
-            reject(`queryUrl failed after 10 second.`);
+            reject(failMsg);
             clearTimeout(timeOut);
-        }, 10000);
+        }, failedTimeOut);
         loop();
 
         function loop() {
-            chrome.tabs.sendMessage(tab.id, req, url => {
+            chrome.tabs.sendMessage(tab.id, req, r => {
-                if (url && (!urlExcluded || (urlExcluded && urlExcluded != url))) {
+                if (cond(r)) {
-                    resolve(url);
+                    resolve(r);
                     clearTimeout(rejectTimeout);
                 } else {
                     timeOut = setTimeout(() => {
                         loop();
-                    }, 500);
+                    }, detectInterval);
                 }
             });
         }
     });
-}
-
-function createTab(url) {
-    return new Promise((resolve, reject) => {
-        chrome.tabs.create({
-            active: true,
-            url: url
-        }, function (tab) {
-            resolve(tab);
-        });
-    });
 }