How do I lowercase any input into this function? https://www.codecademy.com/paths/full-stack-engineer-career-path/tracks/fscp-javascript-syntax-part-i/modules/fecp-learn-javascript-syntax-functions/projects/sleep-debt-calculator

const getSleepHours = day => {

day.toLowerCase();

if (day === ‘monday’) {

return '8'

} else if (day === ‘tuesday’) {

return '10'

} else if (day === ‘wednesday’) {

return '7'

} else if (day === ‘thursday’) {

return '7'

} else if (day === ‘friday’) {

return '9'

} else if (day === ‘saturday’) {

return '6'

} else if (day === ‘sunday’) {

return '10'

} else {

console.log('invalid day')

}

}

console.log(getSleepHours(‘Thursday’))
I included day.toLowerCase(); but it still makes
console.log(getSleepHours(‘Thursday’)) an invalid day.

Reassign the variable like:
day = day.toLowerCase();