add GM.getTab and GM.saveTab

README.md

@@ -191,6 +191,11 @@ Userscripts currently supports the following api methods. All methods are asynch
     - on success returns a promise resolved with an object indicating success
 - `GM.listValues()`
     - on success returns a promise resolved with an array of the key names of **presently set** values
+- `GM.getTab()`
+    - on success returns a promise resolved with `Any` data that is persistent as long as this tab is open
+- `GM.saveTab(tabObj)`
+    - `tabObj: Any`
+    - on success returns a promise resolved with an object indicating success
 - `GM.openInTab(url, openInBackground)`
     - `url: String`, `openInBackground: Bool`
     - on success returns a promise resolved with the [tab data](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/Tab) for the tab just opened

extension/Userscripts Extension/Resources/background.js

@@ -158,6 +158,53 @@ const apis = {
         window.postMessage({id: US_uid, name: "API_SET_CLIPBOARD", data: data, type: type});
         return undefined;
     },
+    US_getTab() {
+        const pid = Math.random().toString(36).substring(1, 9);
+        return new Promise(resolve => {
+            const callback = e => {
+                if (
+                    e.data.pid !== pid
+                    || e.data.id !== US_uid
+                    || e.data.name !== "RESP_GET_TAB"
+                    || e.data.filename !== US_filename
+                ) return;
+                const response = e.data.response;
+                resolve(response);
+                window.removeEventListener("message", callback);
+            };
+            window.addEventListener("message", callback);
+            window.postMessage({
+                id: US_uid,
+                pid: pid,
+                name: "API_GET_TAB",
+                filename: US_filename
+            });
+        });
+    },
+    US_saveTab(tab) {
+        const pid = Math.random().toString(36).substring(1, 9);
+        return new Promise(resolve => {
+            const callback = e => {
+                if (
+                    e.data.pid !== pid
+                    || e.data.id !== US_uid
+                    || e.data.name !== "RESP_SAVE_TAB"
+                    || e.data.filename !== US_filename
+                ) return;
+                const response = e.data.response;
+                resolve(response);
+                window.removeEventListener("message", callback);
+            };
+            window.addEventListener("message", callback);
+            window.postMessage({
+                id: US_uid,
+                pid: pid,
+                name: "API_SAVE_TAB",
+                filename: US_filename,
+                tab: tab
+            });
+        });
+    },
     // when xhr is called it sends a message to the content script
     // and adds it's own event listener to get responses from content script
     // each xhr has a unique id so it won't respond to different xhr
@@ -405,6 +452,14 @@ function addApis({userscripts, uid, scriptHandler, scriptHandlerVersion}) {
                     api += `\n${apis.US_setClipboardSync}`;
                     api += "\nconst GM_setClipboard = US_setClipboardSync;";
                     break;
+                case "GM.getTab":
+                    api += `\n${apis.US_getTab}`;
+                    gmMethods.push("getTab: US_getTab");
+                    break;
+                case "GM.saveTab":
+                    api += `\n${apis.US_saveTab}`;
+                    gmMethods.push("saveTab: US_saveTab");
+                    break;
                 case "GM_xmlhttpRequest":
                 case "GM.xmlHttpRequest":
                     if (!includedMethods.includes("xhr")) {
@@ -713,6 +768,33 @@ browser.runtime.onMessage.addListener((request, sender, sendResponse) => {
             }
             break;
         }
+        case "API_GET_TAB": {
+            if (typeof sender.tab !== "undefined") {
+                let tab = null;
+                const tabData = sessionStorage.getItem(`tab-${sender.tab.id}`);
+                try {
+                    // if tabData is null, can still parse it and return that
+                    tab = JSON.parse(tabData);
+                } catch (error) {
+                    console.error("failed to parse tab data for getTab");
+                }
+                sendResponse(tab);
+            } else {
+                console.error("unable to deliver tab due to empty tab id");
+                sendResponse(null);
+            }
+            break;
+        }
+        case "API_SAVE_TAB": {
+            if (typeof sender.tab !== "undefined" && request.tab) {
+                sessionStorage.setItem(`tab-${sender.tab.id}`, JSON.stringify(request.tab));
+                sendResponse({success: true});
+            } else {
+                console.error("unable to save tab due to empty tab id or bad arg");
+                sendResponse(null);
+            }
+            break;
+        }
         case "USERSCRIPT_INSTALL_00":
         case "USERSCRIPT_INSTALL_01":
         case "USERSCRIPT_INSTALL_02": {

extension/Userscripts Extension/Resources/content.js

@@ -245,6 +245,31 @@ function handleApiMessages(e) {
                 window.postMessage(respMessage);
             });
             break;
+        case "API_GET_TAB":
+            message = {
+                name: name,
+                filename: e.data.filename,
+                pid: pid
+            };
+            browser.runtime.sendMessage(message, response => {
+                respMessage.response = response;
+                respMessage.filename = e.data.filename;
+                window.postMessage(respMessage);
+            });
+            break;
+        case "API_SAVE_TAB":
+            message = {
+                name: name,
+                filename: e.data.filename,
+                pid: pid,
+                tab: e.data.tab
+            };
+            browser.runtime.sendMessage(message, response => {
+                respMessage.response = response;
+                respMessage.filename = e.data.filename;
+                window.postMessage(respMessage);
+            });
+            break;
         case "API_XHR_ABORT_INJ":
             message = {name: "API_XHR_ABORT_CS", xhrId: e.data.xhrId};
             browser.runtime.sendMessage(message);

src/page/utils.js

@@ -152,7 +152,9 @@ export const validGrants = new Set([
     "GM_addStyle",
     "GM_info",
     "GM_setClipboard",
-    "GM_xmlhttpRequest"
+    "GM_xmlhttpRequest",
+    "GM.getTab",
+    "GM.saveTab"
 ]);
 
 export const validKeys = new Set([