Brute force diff & patch lists

listdiff.js

function fixup(a, b) {
	console.log(a, '=>', b);
	var add = [];
	var remove = [];
	for (var i = 0; i < a.length; i++) {
		if (b.indexOf(a[i]) == -1) {
			remove.push(a[i]);
		}
	}
	for (var i = 0; i < b.length; i++) {
		if (a.indexOf(b[i]) == -1) {
			add.push(b[i]);
		}
	}
	
	var fin = a;
	remove.forEach((c) => {
		fin = drop(fin, fin.indexOf(c));
	})
	add.forEach((c) => {
		fin = insert(fin, b.indexOf(c), c);
	})
	
	for (var i = 0; i < fin.length; i++) {
		if (fin[i] !== b[i]) {
			fin = insert(fin, i, b[i]);
		}
	}
	console.log('---');
	return fin;
}

function insert(s, idx, c) {
	var p = s.indexOf(c);
	if (p !== -1) {
		s = s.substring(0, p) + s.substring(p+1);
	}
	console.log('insert ->', c, idx);
	return s.substring(0, idx) + c + s.substring(idx);
}

function drop(s, idx) {
	console.log('drop ->', s[idx], idx);
	return s.substring(0, idx) + s.substring(idx+1);
}

var mutations = [
	["abcdefgh", "bcdefghi"],
	["abcdefgh", "bdcefghi"],
	["abcdefgh", "abcidefgh"],
	["abcdefgh", "defghabc"]
];

mutations.forEach((m) => {
	var fin = fixup(m[0], m[1]);
	if (fin === m[1]) {
		console.log('OK\n---\n');
	} else {
		console.log('FAIL\n---\n');
	}
	
});

stdout.txt

abcdefgh => bcdefghi
drop -> a 0
insert -> i 7
---
OK
---

abcdefgh => bdcefghi
drop -> a 0
insert -> i 7
insert -> d 1
---
OK
---

abcdefgh => abcidefgh
insert -> i 3
---
OK
---

abcdefgh => defghabc
insert -> d 0
insert -> e 1
insert -> f 2
insert -> g 3
insert -> h 4
---
OK
---