Google's interview question (https://www.youtube.com/watch?v=10WnvBk9sZc)

longest-common-subsequence.js

const input = [
    ['', ''],
    ['ABAZDC', 'BACBAD'],
    ['BACBAD', 'ABAZDC'],
    ['AGGTAB', 'GXTXAYB'],
    ['ABBA', 'BABAABAB'],
    ['GT', 'XCDFGRGDTRIFG'],
];

const output = [
    '',
    'ABAD',
    'ABAD',
    'GTAB',
    'ABBA',
    'GT',
];

const algo = ([str1, str2]) => {
    function findSequence(string1, string2) {
        let sequence = '';
        let prevCharAt = 0;

        string1.split('').forEach((char) => {
            const charAt = string2.substr(prevCharAt).indexOf(char);

            if (charAt > -1) {
                prevCharAt = prevCharAt + charAt + 1;
                sequence += char;
            }
        });

        return sequence;
    }

    const sequense = findSequence(str1, str2);
    const sequense2 = findSequence(str2, str1);

    return sequense.length > sequense2.length ? sequense : sequense2;
};

const result = input.map(algo);
const valid = JSON.stringify(output) === JSON.stringify(result);

console.log('valid: ', valid);  // To be true