Add factoryWithSeed snippet

snippets/factoryWithSeed.md

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+---
+title: factoryWithSeed
+tags: array,beginner
+---
+
+Generates the given amount of objects based on the given factory, which receives a unique seed.
+
+- Creates a new array of size `amount`.
+- Fills it with some value to be able to iterate over it via `map`.
+- Uses `map`'s second argument, the index, as a seed for the factory.
+
+```js
+const factoryWithSeed = (amount, factory) =>
+  Array(amount) // create array with so many empty slots
+   .fill(0) // fill them to be able to iterate
+   .map((_, i) => factory(i)) // use index as seed
+```
+
+```js
+const mockData = factoryWithSeed(5000, seed => ({ id: seed, name: randomAlphaNumeric(10) }));
+// 5000 items with unique IDs
+```