Javascript Codewars Challenge(isMerge)

Question

I have asked this question before (the first link to my question) but couldn\'t get the complete solution for the question. Write an algorithm to check if a given string, s, can

Answer 1

function isMerge(s, part1, part2) {
            if (part1.length === 0) {
                return (s == part2);
            }
            if (part2.length === 0) {
                return (s == part1);
            }
            if (s.length === 0) {
                return false;
            } /*because if you are still here, part 1 and part 2 are not empty*/
            /*handle empty strings first both as "base case" and to not have to worry about expressions like s[0]*/
            return ((s[0] == part1[0]) && isMerge(s.substr(1), part1.substr(1), part2)) || ((s[0] == part2[0]) && isMerge(s.substr(1), part1, part2.substr(1)));
        }
        // example 1
        {
            let str = 'codewars'
            let part1 = 'cdw'
            let part2 = 'oears'
            console.log(isMerge(str, part1, part2)) // true
        }

        // example 2
        {
            let str = 'codewars'
            let part1 = 'cdb'
            let part2 = 'oears'
            console.log(isMerge(str, part1, part2)) // false
        }