How to set conditions for displaying models in different formats in threejs?

Question

JavaScript

Good afternoon everyone, I can’t figure out how to implement display by formats, each format has its own controllers.
The glb format has such an output, I can’t find how to set conditions if the format is glb, then it is output by glb, if the format is stl, then another, and so on

const ktx2Loader = new KTX2Loader()
          .setTranscoderPath( 'threejs_3d/examples/js/libs/basis/' )
          .detectSupport( renderer );

        const loader = new GLTFLoader().setPath( 'models/gltf/' );
        loader.setKTX2Loader( ktx2Loader );
        loader.setMeshoptDecoder( MeshoptDecoder );
        loader.load( 'coffeemat.glb', function ( gltf ) {

          // coffeemat.glb was produced from the source scene using gltfpack:
          // gltfpack -i coffeemat/scene.gltf -o coffeemat.glb -cc -tc
          // The resulting model uses EXT_meshopt_compression (for geometry) and KHR_texture_basisu (for texture compression using ETC1S/BasisLZ)

          gltf.scene.position.y = 8;

          scene.add( gltf.scene );

          render();

        } );