205-isomorphic-strings

/**
 * @param {string} s
 * @param {string} t
 * @return {boolean}
 */
var isIsomorphic = function(s, t) {
    let codex = {};
    let codexValues = [];
    for (let i = 0; i < s.length; ++i) {
        const targetChar = s.charAt(i);
        if (codex.hasOwnProperty(targetChar)) {
            if (t.charAt(i) !== codex[targetChar]) return false
            else continue;
        }
        else if (codexValues.includes(t.charAt(i))) return false
        else {
            codex[targetChar] = t.charAt(i);
            codexValues.push(t.charAt(i));
        }
    };
    return true;
};

/**
 * Notes:
 * Two strings s and t are isomorphic if the characters in s can be replaced to get t
 * Example: s = "egg", t = "add" - true
 * Example: s = "foo", t = "bar" - false, because the first instance of o maps to a, and may not then map to r
 */