three.js/src/lights/RectAreaLight.js

import { Light } from './Light.js';

function RectAreaLight( color, intensity, width, height ) {

	Light.call( this, color, intensity );

	this.type = 'RectAreaLight';

	this.width = ( width !== undefined ) ? width : 10;
	this.height = ( height !== undefined ) ? height : 10;

}

RectAreaLight.prototype = Object.assign( Object.create( Light.prototype ), {

	constructor: RectAreaLight,

	isRectAreaLight: true,

	copy: function ( source ) {

		Light.prototype.copy.call( this, source );

		this.width = source.width;
		this.height = source.height;

		return this;

	},

	toJSON: function ( meta ) {

		const data = Light.prototype.toJSON.call( this, meta );

		data.object.width = this.width;
		data.object.height = this.height;

		return data;

	}

} );

export { RectAreaLight };