Play a Mixamo exported animation with model (converted to JSON format) in three.js

mixamoAnim.js

var scene,
    camera,
    light,
    renderer,
    timer,
    manager;

function init(){
    manager = new THREE.LoadingManager();  
    //Don't start rendering until you finish loading
    manager.onload = function(){
      render();
    }
    
    timer = new THREE.Clock();
    scene = new THREE.Scene();
    camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.01, 10000);
    camera.position.set(0, 0.11, 1);

    light = new THREE.DirectionalLight(0xffffff);
    scene.add(light);
  
    renderer = new THREE.WebGLRenderer();
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.setPixelRatio(window.devicePixelRatio);
    renderer.sortObjects = false;
    document.body.appendChild(renderer.domElement);
  
      var animLoader = new THREE.JSONLoader(manager);
  
      animLoader.load('assets/mixamoAnim.json', function(geometry, materials){
          var mat = new THREE.MeshBasicMaterial();
          //Make sure to use the vertex colors and skin the material
          mat.vertexColors = THREE.VertexColors;
          //This is false by default and will not animate!
          mat.skinning = true;
        
          var skinnedMesh = new THREE.SkinnedMesh(geometry, mat);
        
          mixer = new THREE.AnimationMixer(skinnedMesh);
          //Pick the first animation track
          var animation = mixer.clipAction(geometry.animations[ 0 ]);

          scene.add(skinnedMesh);
        
          animation.play();

      });
  
}

function render(){
      requestAnimationFrame(render);
      mixer.update(timer.getDelta());
      renderer.render(scene, camera);
}