MinWindowSubstring.js

var arr = ["abcdefbghijklabop", "bl"];

function getShortestSub(dic) {
    var shortestlen = Infinity;
    var substring = "";
    for( var key in dic ) {
        if (dic[key].length < shortestlen) {
            shortestlen = dic[key].length;
            substring = dic[key];
        }
    }
    return substring;
}

function substringHelper(i, string, characters, strings) {
    if (i in strings) {
        return;
    }
    var tempDic = {};
    for (var key in characters) {
        tempDic[key] = characters[key];
    }
    var tempStr = "";
    var j = i;
    while (i < string.length) {

        if (string[i] in tempDic) {
            tempDic[string[i]]--;
            tempStr += string[i];
            i++;
            substringHelper(i, string, characters, strings);

            var isntDone = false;
            for (var key in tempDic) {
                if (tempDic[key] > 0) {
                    isntDone = true;
                }
            }
            if (isntDone) {
                continue;
            }
            else {
                strings[j] = tempStr;
                return;
            }
        }
        else {
            tempStr += string[i];
            i++;
        }
    }
}

function MinWindowSubstring(strArr) {
    var potStrings = {};
    var charCounts = {};
    var string = strArr[0];
    var chars = strArr[1];
    for (var i = 0; i < chars.length; i++) {
        if (chars[i] in charCounts) {
            charCounts[chars[i]]++;
        }
        else {
            charCounts[chars[i]] = 1;
        }
    }
    var j = 0;
    while (j < string.length) {
        if (!(string[j] in charCounts)) {
            j++;
            continue;
        }
        else {
            substringHelper(j, string, charCounts, potStrings);
        }
        j++;
    }
    return getShortestSub(potStrings);
}

// keep this function call here
console.log(MinWindowSubstring(arr));