You will find here all loading plugin that you can use to load different formats than .babylon
To use then you just have to reference the loader file:
<script src="Babylon.js"></script>
<script src="babylon.stlFileLoader.js"></script>
And then the SceneLoader will know how to load the new extension:
BABYLON.SceneLoader.Load("/Files/", "ch9.stl", engine, function (newScene) {
newScene.activeCamera.attachControl(canvas, false);
engine.runRenderLoop(function () {
newScene.render();
});
});