refactor promise, geneerators, global object

1-js/09-async/07-async-iteration-generators/article.md

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+# Async iteration and generators
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+In web-programming, we often need to work with fragmented data that comes piece-by-piece.
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+That happens when we upload or download a file. Or we need to fetch paginated data.
+
+
+For
+Either we need to download or upload something, or we need
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+In the previous chapter we saw how `async/await` allows to write asynchronous code.
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+But they don't solve
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+
+
+Regular iterators work fine with the data that doesn't take time to generate.
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+A `for..of` loop assumes that we