Function subtractLeftFrequency

javascript/0076-minimum-window-substring.js:64–75

(s, left, frequencyMap, matched)

};

const subtractLeftFrequency = (s, left, frequencyMap, matched) => {
    const char = s[left];

    if (frequencyMap.has(char)) {
        const isOutOfWindow = frequencyMap.get(char) === 0;
        if (isOutOfWindow) matched--;

        frequencyMap.set(char, frequencyMap.get(char) + 1);
    }

    return matched;
};

const getSubString = (s, start, end) =>
    end <= s.length ? s.slice(start, start + end) : '';