'Confused on github copilot solution that works but not sure why

So I was stuck on a bug in my React App (I am new to react and JS in general) where I wanted to filter a list of company names so that they are all unique and dont repeat. So having access to github copilot I turned it on and out came a solution that worked but I have no idea why or what its doing. If anyone could help me?

    useEffect(() => {
        const companyNames = data.map(app => app.companyName);
        const uniqueCompanies = [...new Set(companyNames)];
        setCompanies(uniqueCompanies);
    },[data]);

I dont understand how [...new Set(companyNames)] filters out the unique names or what is happening. To my understanding you can only use the spread operator on an array that already exists so didn't know where the new was coming from either.

javascript reactjs

Solution 1:^[1]

The expression const uniqueCompanies = [...new Set(companyNames)]; contains the following interesting properties:

[] is an array literal
new Set(companyNames) a new JavaScript Set that can contain only unique values by design, providing the filtering "out of the box".
... The array spread operator here will spread the Set to Array, thus effectively converting the Set to Array.

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Solution 1	LauriM

'Confused on github copilot solution that works but not sure why

Solution 1:[1]

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Solution 1:^[1]