Loading Screen for my assessment

I have finally started on my assessment and i was able to make a loading bar by coding in the background and the bar. All I've got to do now is find a way to make the bar move from left to right. I know I've got to add something in the LoadingScene script, but i am still trying to figure out what to add in there.

constructor(engine)
    {
        super(engine);

        this.loader = new AssetLoader(this);
        /*Load assets here*/

        const backgroundEntity = new Entity(this, 320, 300);
        new Image(backgroundEntity, "splashBackground")

        const loadingBarBackground = new Entity(this, 320, 650)
        new Image(loadingBarBackground, "loadingBarBackground")

        const loadingBarFill = new Entity(this, 320, 650)
        new Image(loadingBarFill, "loadingBarFill");
        
        const textEntity = new Entity(this, 250, 600);
        new TextField(textEntity, "Loading...", new TextFieldConfig("Arial", "40px", "#FFFFFF", TextAlign.BOTTOM));
    }