6.js

function calculateSurfaceArea(dimensions) {
   let sides = [2 * (dimensions[0] * dimensions[1] ), 2 * (dimensions[1] * dimensions[2]), 2 * (dimensions[0] * dimensions[2] )];
   return sides[0] + sides[1] + sides[2];
}

And the calculateVolume function looks like this

function calculateVolume(dimensions) {
   return dimensions[0] * dimensions[1] * dimensions[2];
}