Replacing complex conditions with descriptive variables

A few well-named variables go a long way towards making code more self-explanatory. Readability is worth a few extra lines; your future self will thank you!

// before: it’s hard to see what this combination of conditions does
if (!(currentDay === 'Saturday' || currentDay === 'Sunday') &&
    currentHour >= 9 && currentHour <= 18) {
  return 'The store is open!'

// after: by assigning the conditions to variables, we can use their names
// to explain the logic behind our code in plain language
const isSaturday = currentDay === 'Saturday'
const isSunday = currentDay === 'Sunday'

const isWeekend = isSaturday || isSunday

const isDuringBusinessHours = currentHour >= 9 && currentHour <= 18

if (!isWeekend && isDuringBusinessHours) {
  return 'The store is open!'

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