three.js/examples/js/loaders/VRMLoader.js

( function () {

	//
	// VRM is based on glTF 2.0 and VRM extension is defined
	// in top-level json.extensions.VRM

	var VRMLoader = function () {

		function VRMLoader( manager ) {

			if ( THREE.GLTFLoader === undefined ) {

				throw new Error( 'THREE.VRMLoader: Import THREE.GLTFLoader.' );

			}

			THREE.Loader.call( this, manager );
			this.gltfLoader = new THREE.GLTFLoader( this.manager );

		}

		VRMLoader.prototype = Object.assign( Object.create( THREE.Loader.prototype ), {
			constructor: VRMLoader,
			load: function ( url, onLoad, onProgress, onError ) {

				var scope = this;
				this.gltfLoader.load( url, function ( gltf ) {

					try {

						scope.parse( gltf, onLoad );

					} catch ( e ) {

						if ( onError ) {

							onError( e );

						} else {

							console.error( e );

						}

						scope.manager.itemError( url );

					}

				}, onProgress, onError );

			},
			setDRACOLoader: function ( dracoLoader ) {

				this.gltfLoader.setDRACOLoader( dracoLoader );
				return this;

			},
			parse: function ( gltf, onLoad ) {

				// var gltfParser = gltf.parser;
				// var gltfExtensions = gltf.userData.gltfExtensions || {};
				// var vrmExtension = gltfExtensions.VRM || {};
				// handle VRM Extension here
				onLoad( gltf );

			}
		} );
		return VRMLoader;

	}();

	THREE.VRMLoader = VRMLoader;

} )();