derive enum flags

deriveEnumFlags.js

const daysEnum = {
	1: 'Sun',
	'Sun': 1,
	2: 'Mon',
	'Mon': 2,
	4: 'Tue',
	'Tue': 4,
	8: 'Wed',
	'Wed': 8,
	16: 'Thu',
	'Thu': 16,
	32: 'Fri',
	'Fri': 32,
	64: 'Sat',
	'Sat': 64,
}

const deriveEnumFlags = (val, enums) => {
	let num = val
	let matches = []

	let entries = Object.entries(enums).filter((x) => !isNaN(x[0]))
	
	for (let i = entries.length - 1; i >= 0; i--) {
		
		let entry = entries[i]
		
		let key = +entry[0]
		let val = entry[1]
	
		if (num - key >= 0) {
			num = num - key
			matches.push(val)
		}
	}

	return matches
}


console.log(deriveEnumFlags(daysEnum.Mon + daysEnum.Sat + daysEnum.Fri, daysEnum))