code now works as intended

background.js

@@ -1,33 +1,97 @@
-console.log("background.js starts now");
+console.log("background.js started");
+
+var baseUrl = "";
+
+function getCurrentDate() {
+  let today = new Date();
+  let yyyy = today.getFullYear();
+  let mm = String(today.getMonth() + 1).padStart(2, '0'); //January is 0!
+  let dd = String(today.getDate()).padStart(2, '0');
+  return yyyy + mm + dd;
+}
+
+function onSuccess(result) {
+  console.log(`background.js: onSuccess(): Promise resolved with result '${JSON.stringify(result)}'`); 
+}
+
+function onFailure(error) {
+  console.log(`background.js: onFailure(): Promise rejected with error '${error}'`);
+}
+
+async function downloadFile(url, filename, saveAs=false) {
+  console.log(`background.js: downloadFile(): url is '${url}' and filename is '${filename}'`);
+  return browser.downloads.download({
+    url: new URL(url, baseUrl).toString(),
+    filename: filename,
+    saveAs: saveAs  // raise a path chooser dialog if true
+  });
+}
+
+async function downloadAllFiles(urlsAndFilenames) {
+  console.log(`background.js: downloadAllFiles(): started with ${JSON.stringify(urlsAndFilenames)}`);
+  const currentDate = getCurrentDate();
+
+  for (const urlAndFilename of urlsAndFilenames) {
+    let prefixedFilename = currentDate + " " + urlAndFilename.filename;
+    await downloadFile(urlAndFilename.url, prefixedFilename, true).then(onSuccess, onFailure);
+  }
+/*
+  for (let i = 0; i < urlsAndFilenames.length; i++) {
+    // prefix filename
+    let prefixedFilename = currentDate + " " + urlsAndFilenames[i].filename;
+    console.log(`background.js: downloadAllFiles(): i is ${i}`);
+//    if ( i == 0 ) {
+      await downloadFile(urlsAndFilenames[i].url, prefixedFilename, true).then(onSuccess, onFailure);
+//    } else {
+//      downloadFile(urlsAndFilenames[i].url, prefixedFilename).then(onSuccess, onFailure);
+//    }
+  }
+*/
+}
 
 function handlePageactionClick(tab, onClickData) {
-  console.log("background.js: executing content script");
+  console.log("background.js: handlePageactionClick(): executing content script");
-  let executing = browser.scripting.executeScript({
+  
+  // get base url
+  browser.tabs.query(
+    {
+      currentWindow: true, 
+      active: true
+    }
+  )
+  .then(
+    tabs => {
+      console.log(`background.js: handlePageactionClick(): tab query returned ${JSON.stringify(tabs)}`);
+      baseUrl = tabs[0].url;
+    }
+  )
+  
+  // execute content script
+  browser.scripting.executeScript(
+    {
       files: [ "/contentscript.js" ],
-    target: {
+      target: 
+      {
         tabId: tab.id,
         allFrames: false
       }
-  });
+    }
-  executing.then(onExecuted, onExecutionError);
+  )
+  .then(results => {
+    console.log(`background.js: handlePageactionClick(): content script execution successful with results '${JSON.stringify(results)}'`);
+    results.forEach(r => downloadAllFiles(r.result));
+  })
+  .catch(error => 
+    console.error(`background.js: handlePageactionClick(): The following error occured while executing a content script: ${error}`)
+  )
 }
 
-function onExecuted(result) {
+/*
-  console.log(`background.js: content script execution successful with result: ${JSON.stringify(result)}`);
-}
-
-
-function onExecutionError(error) {
-  console.error(`background.js: The following error occured while executing a content script: ${error}`);
-}
-
-
 let gettingAllPermissions = browser.permissions.getAll();
 gettingAllPermissions.then((allPermissions) => { 
   console.log(JSON.stringify(allPermissions))
 });
-
+*/
-
 
 // add listener for the extension button
 browser.pageAction.onClicked.addListener(handlePageactionClick);

contentscript.js

@@ -1,25 +1,15 @@
 console.log("contentscript.js started!");
 
-function getCurrentDate() {
+function extractUrlsAndFilenames() {
-  let today = new Date();
+  console.log("contentscript.js: this is extractFileUrlsAndNames()");
-  let yyyy = today.getFullYear();
-  let mm = String(today.getMonth() + 1).padStart(2, '0'); //January is 0!
-  let dd = String(today.getDate()).padStart(2, '0');
-  return yyyy + "-" + mm + "-" + dd;
-}
-
-function extractFileUrlsAndNames() {
-console.log("contentscript.js: this is extractFileUrlsAndNames()");
   // get the correct frame
   let frame = document.querySelector("iframe.js-mail-content");
   
   // get all divs containing attachments
   let divs = frame.contentWindow.document.body.querySelectorAll("div.samoware-mail-message__attach__item[attachment-ref]"); 
-  console.log(`contentscript.js: found ${divs.length} div containing attachments`);
-  
-  let urlsAndFilenames = []
 
   // loop over divs and extract attachment information
+  let urlsAndFilenames = []
   divs.forEach(div => {
     let url = div.getAttribute("attachment-ref");
     let filename = div.getAttribute("file-name");
@@ -31,41 +21,9 @@ console.log("contentscript.js: this is extractFileUrlsAndNames()");
     }
     urlsAndFilenames.push({url: url, filename: filename});
   })
-
-  //console.log(`contentscript.js: urlsAndFilenames is ${JSON.stringify(urlsAndFilenames)}`);
   return urlsAndFilenames;
 }
 
-function onStartedDownload(id) {
+const urlsAndFilenames = extractUrlsAndFilenames();
-  console.log(`contentscript.js: Started downloading: ${id}`);
+console.log(`contentscript.js: done; found ${JSON.stringify(urlsAndFilenames)}`);
-}
+urlsAndFilenames;
-
-function onFailedToStartDownload(error) {
-  console.log(`contentscript.js: Download failed: ${error}`);
-}
-
-// get today's date
-let currentDate = getCurrentDate();
-console.log(`contentscript.js: currentDate is ${currentDate}`);
-
-let urlsAndFilenames = extractFileUrlsAndNames();
-
-// loop over attachments
-for (let i = 0; i < urlsAndFilenames.length; i++) {
-  // prefix filename
-  let prefixedFilename = currentDate + " - " + urlsAndFilenames[i].filename;
-console.log(`contentscript.js: prefixedFilename is ${prefixedFilename}`);
-
-  // start download
-  let downloading = browser.downloads.download({
-    url: urlsAndFilenames[i].url,
-    filename: prefixedFilename,
-    saveAs: i == 0   // raise a path chooser dialog for the first file only; all later files will (hopefully!) be saved to the same folder
-  });
-  console.log(`contentscript.js: downloading is ${downloading}`);
-  // resolve Promise
-  downloading.then(onStartedDownload, onFailedToStartDownload);
-} 
-
-console.log("contentscript.js: has finished");
-"contentscript.js: this is the final line";