Connect FBX File Morph Targets and Bones to dat.gui

Questions
2

JSONLoader creates Geometry while newer loaders create BufferGeometry, so there are slight differences but I think this should work for both:

folder.add( mesh.morphTargetInfluences, '0', 0, 1 ).step( 0.01 ).name('A').listen();
folder.add( mesh.morphTargetInfluences, '1', 0, 1 ).step( 0.01 ).name('B').listen();
folder.add( mesh.morphTargetInfluences, '2', 0, 1 ).step( 0.01 ).name('C').listen();
folder.add( mesh.morphTargetInfluences, '3', 0, 1 ).step( 0.01 ).name('D').listen();

Using a GUI to control bones will get messy with many bones but the basics are simple enough:

folder.add( bone.rotation, 'y', 0, 360 ).name( 'Arm' );