Taming the DOM withuseLayoutEffect and useRef
When layout-sensitive logic has to run before paint, this pair gives you precise control without the flash that often comes with a regular effect.
Read Articlejest.fn() vs jest.mock()Know the Difference
Both create fakes. But one replaces a function, the other replaces an entire module, and confusing the two leads to tests that do not work the way you think.
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