Algorithms - Multiple Pointers

isSubsequence.js

function isSubsequence(first, second) {
    if (first.length > second.length) return false;

    if (!first) return true;

    let i = 0;
    let j = 0;

    while (j < second.length) {
        if (first[i] === second[j]) i++;
        if (i === first.length) return true;
        j++;
    }

    return false;

}