[Slider] Fix

slider/ts/slider.ts

@@ -181,7 +181,6 @@ var loadImageType = ( name: string ) => {
         const baseURL = el.dataset.imageBaseURL;
         const filetype = el.dataset.filetype;
 
-        // TODO: Verification (i.e. baseURL cannot contain .something in the end, filetype may only be jpg, jpeg, webp, svg or png)
         if ( allowedExtensions.indexOf( filetype ) === -1 ) {
             console.warn( '[ SLIDER ] Invalid filetype ' + filetype + ' for image element with id ' + el.id );
 
@@ -194,7 +193,7 @@ var loadImageType = ( name: string ) => {
             return;
         }
 
-        el.style.setProperty( 'background-image', baseURL + name + filetype );
+        el.style.setProperty( 'background-image', `url(${ baseURL }${ name }${ filetype })` );
     } );
 };