Redux

Calling an API will cause side-effects, and thus a function that calls an API is considered an impure function. Read more

Shallow-merge and deep merge:

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const obj1 = { a: 1, b: { x: 10, y: 20 } };
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const obj2 = { b: { z: 30 } };
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const shallowMerged = { ...obj1, ...obj2 };
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console.log(shallowMerged);
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// Output: { a: 1, b: { z: 30 } }
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const deepMerged = deepMerge(obj1, obj2);
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console.log(deepMerged);
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// Output: { a: 1, b: { x: 10, y: 20, z: 30 } }