How to use the nativescript-sqlite.exists function in nativescript-sqlite

public openDB(){
        let instance= this;
        //CHECK IF IT EXISTS AND IF ITS OPEN
        if(Sqlite.exists("MyDB")){
            if(instance.db.isOpen()){
                console.log("DB is already open!");
                instance.info = "DB is already open!";
            } else {
                var db_promise = new Sqlite("MyDB", false, (err, db)=>{
                    if (err) { 
                    console.error("We failed to open database", err);
                    instance.info = "We failed to open database " + err;
                    } else {
                    console.log("Are we open yet (Inside Callback)? ", db.isOpen() ? "Yes" : "No"); // Yes
                    instance.info = "DB opened";
                    instance.db = db;
                    }
                });
            }

exports.pageLoaded = function(args) {
	page = args.object;
	page.bindingContext = {names: data};

	if (!sqlite.exists(dbname)) {
		sqlite.copyDatabase(dbname);
	}
	new sqlite(dbname, {key: 'testing', multithreading: !!sqlite.HAS_COMMERCIAL, migrate: true}, function(err, dbConnection) {
		if (err) {
			console.log(err, err.stack);
		}
		db = dbConnection;
		db.resultType(sqlite.RESULTSASOBJECT);

		db.version().then(function (results) {
			console.log("User Version: ", results, typeof results, Number.isNumber(results)); //, String.isString(results));
		});

		if (sqlite.HAS_ENCRYPTION) {
			db.get("PRAGMA cipher_version;").then(function(results) {
				console.log("Cipher version", results['cipher_version']);

public closeDB(){
        let instance = this;
        //CHECK IF IT EXISTS AND IF ITS OPEN
        if(Sqlite.exists("MyDB")){
            if(this.db.isOpen()){
                this.db.close((err)=>{
                    if(err){
                        console.log("We failed to close database");
                    } else {
                        console.log("DB closed");
                        instance.info = "DB closed";
                    }
                })
            } else {
                console.log("DB is already closed!");
                instance.info = "DB is already closed!";
            }
            
        } else {
            console.log("DB doesn't exist");

function onCreateConnection(fn, scope) {
  consoleLogMsg("db.service", "createConnection");
  if (!Sqlite.exists(dbFile)) {
    Sqlite.copyDatabase(dbFile);
  }
  dbPromise = new Sqlite(dbName, function (err, dbConnection) {
    if (err) {
      console.error(err);
    } else {
      dbConnection.resultType(Sqlite.RESULTSASOBJECT);
      if (typeof fn === "function") {
        if (scope) {
          fn.apply(scope, [dbConnection]);
        } else {
          fn(dbConnection);
        }
      }
      dbConnection.close();
    }

function AppComponent() {
        if (!Sqlite.exists("highscore.db")) {
            Sqlite.copyDatabase("highscore.db");
        }
    }
    return AppComponent;

public constructor() {
        if (!Sqlite.exists("highscore.db")) {
            Sqlite.copyDatabase("highscore.db");
        }
    }