let planets = [
{ name: 'mars', diameter: 6779 },
]
let planets = [
{ name: 'mars', diameter: 6779 },
{ name: 'earth', diameter: 12742 },
{ name: 'jupiter', diameter: 139820 }
]
let circumferenceReducer = ( c, planet ) => {
return c + planet.diameter * Math.PI;
}
let planets = [
{ name: 'mars', diameter: 6779 },
{ name: 'earth', diameter: 12742 },
{ name: 'jupiter', diameter: 139820 }
]
let c = planets.reduce( circumferenceReducer, 0 )