old_contents: import { Light } from './Light.js';
  import { DirectionalLightShadow } from './DirectionalLightShadow.js';
  import { Object3D } from '../core/Object3D.js';
  
  function DirectionalLight( color, intensity ) {
  
  	Light.call( this, color, intensity );
  
  	this.type = 'DirectionalLight';
  
  	this.position.copy( Object3D.DefaultUp );
  	this.updateMatrix();
  
  	this.target = new Object3D();
  
  	this.shadow = new DirectionalLightShadow();
  
  }
  
  DirectionalLight.prototype = Object.assign( Object.create( Light.prototype ), {
  
  	constructor: DirectionalLight,
  
  	isDirectionalLight: true,
  
  	copy: function ( source ) {
  
  		Light.prototype.copy.call( this, source );
  
  		this.target = source.target.clone();
  
  		this.shadow = source.shadow.clone();
  
  		return this;
  
  	}
  
  } );
  
  
  export { DirectionalLight };
  
new_contents: import { Light } from './Light.js';
  import { DirectionalLightShadow } from './DirectionalLightShadow.js';
  import { Object3D } from '../core/Object3D.js';
  
  class DirectionalLight extends Light {
  
  	constructor( color, intensity ) {
  
  		super( color, intensity );
  
  		Object.defineProperty( this, 'isDirectionalLight', { value: true } );
  
  		this.type = 'DirectionalLight';
  
  		this.position.copy( Object3D.DefaultUp );
  		this.updateMatrix();
  
  		this.target = new Object3D();
  
  		this.shadow = new DirectionalLightShadow();
  
  	}
  
  	copy( source ) {
  
  		super.copy( source );
  
  		this.target = source.target.clone();
  		this.shadow = source.shadow.clone();
  
  		return this;
  
  	}
  
  }
  
  export { DirectionalLight };
  
subject: Convert to ES6 class