threejs GLTF animation

gltf-anim.js

// There's always some fiddling because the GLTF exports a whole scene
// with root bone and skinned mesh already appended to it.

let gltf = loadedGltf;
let skinned;
gltf.scene.traverse(function(object) {
    if (object instanceof THREE.SkinnedMesh) {
        skinned = object;
    }
})
this.mesh = skinned;
this.mesh.material = ... // if you need a custom material, don't forget to set skinning to true

// Important: add the whole gltf scene and use it as root for the mixer
this.add(gltf.scene);
this.mixer = new THREE.AnimationMixer(gltf.scene);
this.animation = this.mixer.clipAction(gltf.animations[0]);