Code Simplicity is the Ultimate Sophistication - https://youtu.be/zxJnyMXhyvw

2-declarative.js

// Imperative: 'what' + 'how'
const makes1 = []
for (let i = 0; i < cars.length; i += 1) {
  makes1.push(cars[i].make)
}

// Declarative: only 'what'
const makes2 = cars.map((car) => car.make)

5-syntax.js

// more syntax: more complex, less readable
const getAction1 = (newPayload, isRejected) => ({
  type: `${type}_${isRejected ? REJECTED : FULFILLED}`,
  ...(newPayload ? { payload: newPayload } : {}),
  ...(!!meta ? { meta } : {}),
  ...(isRejected ? { error: true } : {}),
})

// less syntax: less complex, more readable
const getAction2 = (newPayload, isRejected) => {
  const action = {
    type: `${type}_${isRejected ? REJECTED : FULFILLED}`,
  }
  if (newPayload) {
    action.payload = newPayload
  }
  if (Boolean(meta)) {
    action.meta = meta
  }
  if (isRejected) {
    action.error = true
  }
  return action
}

6-collections.js

const list = [1, 2, 3, 42, 42, 73, 1337]

// unique with reduce
const a = list.reduce(
  (curr, acc) => (curr.includes(acc) ? curr : [...curr, acc]),
  []
)

// unique with filter
const b = list.filter((v, i, a) => a.indexOf(v) === i)

// unique by converting to a Set
const c = Array.from(new Set(list))