constructor() {

    		this.type = 'Curve';

    		this.arcLengthDivisions = 200;

    	}
Extensible curve object.

Some common of curve methods:
.getPoint( t, optionalTarget ), .getTangent( t, optionalTarget )
.getPointAt( u, optionalTarget ), .getTangentAt( u, optionalTarget )
.getPoints(), .getSpacedPoints()
.getLength()
.updateArcLengths()

This following curves inherit from THREE.Curve:

-- 2D curves --
THREE.ArcCurve
THREE.CubicBezierCurve
THREE.EllipseCurve
THREE.LineCurve
THREE.QuadraticBezierCurve
THREE.SplineCurve

-- 3D curves --
THREE.CatmullRomCurve3
THREE.CubicBezierCurve3
THREE.LineCurve3
THREE.QuadraticBezierCurve3

A series of curves can be represented as a THREE.CurvePath.