constructor( x = 0, y = 0, z = 0, w = 1 ) {

		/**
		 * This flag can be used for type testing.
		 *
		 * @type {boolean}
		 * @readonly
		 * @default true
		 */
		this.isQuaternion = true;

		this._x = x;
		this._y = y;
		this._z = z;
		this._w = w;

	}
Constructs a new quaternion.

@param {number} [x=0] - The x value of this quaternion.
@param {number} [y=0] - The y value of this quaternion.
@param {number} [z=0] - The z value of this quaternion.
@param {number} [w=1] - The w value of this quaternion.