mutate-a-word/js/mutate.mjs

"use strict";

const vowels = "aeiou".split("");
const consonants = "bcdfghjklmnpqrstvwxyz".split("");

function random_item(arr) {
	return arr[Math.floor(Math.random() * arr.length)];
}

export default function(word) {
	const chars = word.toLowerCase().split("");
	const targetpos = Math.floor(Math.random() * word.length);
	
	let mode = "replace";
	if(Math.random() < 0.1) mode = "add";
	if(Math.random() > 0.9) mode = "remove";
	
	switch(mode) {
		case "replace":
			const targetchar = chars[targetpos];
			console.log("TARGET", targetchar, "POS", targetpos);
			let pool = consonants.concat(vowels);
			if(vowels.includes(targetchar))
			pool = vowels;
			if(consonants.includes(targetchar))
			pool = consonants;
			
			pool = [...pool]; // Shallow copy to avoid splice mutating the original array
			console.log("POOL BEFORE", pool);
			if(pool.includes(targetchar)) {
				console.log("REMOVING TARGET");
				pool.splice(pool.indexOf(targetchar), 1);
			}
			console.log("POOL AFTER", pool);
			
			let newchar = random_item(pool);
			chars.splice(targetpos, 1, newchar);
			break;
		
		case "add":
			chars.splice(targetpos, 0, random_item(consonants.concat(vowels)));
			break;
		
		case "remove":
			chars.splice(targetpos, 1);
			break;
	}
	return chars.join("");
}