RWC: Cap Permutations

cap-permutations.js

/**
 * Gets all possible capitalizations of the given string
 * @param {string} str string to get capitalization permutations of
 * @returns {string[]} list of all possible capitalization of the given string
 */
function capPermutations(str) {
	let characters = str.split('');
	let permutations = [''];
	for (let character of characters) {
		// Character isn't a capitalizable letter, so tack it on to all visited permutations so far
		if (character.toUpperCase() === character.toLowerCase()) {
			permutations = permutations.map(perm => `${perm}${character}`);
		} else { // Character is a letter, so get all uppercase and lowercase permutations
			const permutationsWithLowercase = permutations.map(perm => `${perm}${character.toLowerCase()}`);
			const permutationsWithUppercase = permutations.map(perm => `${perm}${character.toUpperCase()}`);
			permutations = [...permutationsWithLowercase, ...permutationsWithUppercase];
		}
	}
	return permutations;
}

console.log(capPermutations('ab2'));
console.log(capPermutations('35p'));