code: function() {
  
  		var interpolants = this._controlInterpolants,
  			lastActiveIndex = this._nActiveControlInterpolants ++,
  			interpolant = interpolants[ lastActiveIndex ];
  
  		if ( interpolant === undefined ) {
  
  			interpolant = new THREE.LinearInterpolant(
  					new Float32Array( 2 ), new Float32Array( 2 ),
  						1, this._controlInterpolantsResultBuffer );
  
  			interpolant.__cacheIndex = lastActiveIndex;
  			interpolants[ lastActiveIndex ] = interpolant;
  
  		}
  
  		return interpolant;
  
  	}
docs: Memory management of Interpolants for weight and time scale