I know that there were a lot of topics like this. And I know the basics: .forEach() operates on original array and .map() on the new one.
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The main difference that you need to know is .map() returns a new array while .forEach() doesn't. That is why you see that difference in the output. .forEach() just operates on every value in the array.
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You might also want to check out: - Array.prototype.every() - JavaScript | MDN