Dindaleon

const shields = {
  soccer: {
    'AS Monaco': 'https://i.imgur.com/R0LjeFU.png',
    'Besiktas': 'https://i.imgur.com/zAhnhFt.png',
    'Milan': 'https://i.imgur.com/WiOPhXt.png'
  },
  baseball: {
    'Los Angeles Dodgers': 'https://i.imgur.com/bB0HYgb.png',
    'Houston Astros': 'https://i.imgur.com/gwR11oB.png'
  },

Dindaleon

// Add item to array
// use concat or spread operator

// Remove item from array
// user slice

// Replace item in array
// 

// Source: https://egghead.io/lessons/javascript-redux-avoiding-array-mutations-with-concat-slice-and-spread

Dindaleon

// To remove an item from an array by id:

return state.filter(item => item.id !== action.id)
// To remove a key from an object by id:

let copy = Object.assign({}, state) // assuming you use Object.assign() polyfill!
delete copy[action.id] // shallowly mutating a shallow copy is fine
return copy
// (Bonus) The same with object spread operator proposal: