I've implemented a method to solve the following problem:

Given a dictionary and a text string, find all words from the dictionary that are present in the text. One important point is that if the string is in double quotes, I should treat it a "single" value. If no matches found, the method should return 0.

So for this input:

const text = `Hi. I am a developer. A "Hello world" program was my first code.`;
const dictionary = "hi developer world";

I should get this:

hi
developer
hello
world

This is my current solution:

const fn = (text, dictionary) => {
    const knownWords = dictionary.toLowerCase().split(' ');
    const words = text.toLowerCase().match(/\w+|"[^"]+"/gi);

    const result = words.reduce((acc, word) => {
        if (word[0] == '"') {
            const wordsNoQuotes = word.replace(/"/g, "").split(' ');
            const shouldInclude = wordsNoQuotes.find(word => knownWords.includes(word));
            if (shouldInclude) {
                return acc.concat(wordsNoQuotes);
            }
        } else if (knownWords.includes(word)) {
            acc.push(word)
        }

        return acc;
    }, []);

    return result.length === 0 ? 0 : [...new Set(result)].join('\n');
}

It works ok, but I would like to get some performance related improvements. I am happy to change the code (i.e using indexOf over includes) and so on. Any suggestions are welcome! Thanks.