add api.backupNow() to backend API, closes #4455

src/services/backend_script_api.js

@@ -19,7 +19,8 @@ const SpacedUpdate = require("./spaced_update");
 const specialNotesService = require("./special_notes");
 const branchService = require("./branches");
 const exportService = require("./export/zip");
-const syncMutex = require("./sync_mutex.js");
+const syncMutex = require("./sync_mutex");
+const backupService = require("./backup");
 
 /**
  * <p>This is the main backend API interface for scripts. All the properties and methods are published in the "api" object
@@ -586,6 +587,13 @@ function BackendScriptApi(currentNote, apiParams) {
      */
     this.runOutsideOfSync = syncMutex.doExclusively;
 
+    /**
+     * @method
+     * @param {string} backupName - If the backupName is e.g. "now", then the backup will be written to "backup-now.db" file
+     * @returns {Promise} - resolves once the backup is finished
+     */
+    this.backupNow = backupService.backupNow;
+
     /**
      * This object contains "at your risk" and "no BC guarantees" objects for advanced use cases.
      *