i18n: restore ability to retrieve new i18n strings

## Issue
In the original Desktop code, new strings encountered during runtime will be automatically added to the local `app-strings.json` file. The feature is unavailable in Web because writing to file would require explicit permissions.

## Change
Partially restore the functionality by saving the strings to memory and retrieving it from the console via `copy(window.new_strings)`. It's a little bit of manual work, but I think it is good as it forces a sanity check before committing (previously, experimental/developmental strings are committed and being translated in Transifex).

ui/i18n.js

@@ -2,20 +2,32 @@
 import { isLocalStorageAvailable } from 'util/storage';
 
 const isProduction = process.env.NODE_ENV === 'production';
-let knownMessages = null;
 const localStorageAvailable = isLocalStorageAvailable();
 
 window.i18n_messages = window.i18n_messages || {};
 
-/*
- I dislike the below code (and note that it ships all the way to the distributed app),
- but this seems better than silently having this limitation and future devs not knowing.
+/**
+ * Collects new i18n strings encountered during runtime.
+ * The output can be retrieved and pasted into app-strings.json.
+ *
+ * @param message
  */
 function saveMessageWeb(message) {
-  if (!isProduction && knownMessages === null) {
-    console.log('Note that i18n messages are not saved in web dev mode.'); // eslint-disable-line
-    knownMessages = {};
+  // @if process.env.NODE_ENV!='production'
+  if (!window.app_strings) {
+    return;
   }
+
+  if (!window.new_strings) {
+    console.log('Copy new i18n to clipboard:%c copy(window.new_strings)', 'color:yellow'); // eslint-disable-line
+  }
+
+  window.new_strings = window.new_strings || {};
+
+  if (!window.app_strings[message] && !window.new_strings[message]) {
+    window.new_strings[message] = removeContextMetadata(message);
+  }
+  // @endif
 }
 
 function removeContextMetadata(message) {

ui/redux/actions/settings.js

@@ -15,7 +15,7 @@ import { selectPrefsReady } from 'redux/selectors/sync';
 import { Lbryio } from 'lbryinc';
 import { getDefaultLanguage } from 'util/default-languages';
 
-const { DEFAULT_LANGUAGE } = require('config');
+const { DEFAULT_LANGUAGE, URL_DEV } = require('config');
 const { SDK_SYNC_KEYS } = SHARED_PREFERENCES;
 
 export const IS_MAC = process.platform === 'darwin';
@@ -294,6 +294,16 @@ export function doFetchLanguage(language) {
           });
         });
     }
+
+    // @if process.env.NODE_ENV!='production'
+    if (!window.app_strings) {
+      fetch(`${URL_DEV}/app-strings.json`)
+        .then((r) => r.json())
+        .then((j) => {
+          window.app_strings = j;
+        });
+    }
+    // @endif
   };
 }
 

web/webpack.config.js

@@ -100,6 +100,13 @@ if (fs.existsSync(ROBOTS_TXT_PATH)) {
   });
 }
 
+if (!isProduction) {
+  copyWebpackCommands.push({
+    from: `${STATIC_ROOT}/app-strings.json`,
+    to: `${DIST_ROOT}/app-strings.json`,
+  });
+}
+
 let plugins = [
   new WriteFilePlugin(),
   new CopyWebpackPlugin(copyWebpackCommands),