34 lines
1.1 KiB
Markdown
34 lines
1.1 KiB
Markdown
---
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title: zipWith
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tags: array,advanced
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---
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Creates an array of elements, grouped based on the position in the original arrays and using a function to specify how grouped values should be combined.
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- Check if the last argument provided is a function.
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- Use `Math.max()` to get the longest array in the arguments.
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- Use `Array.from()` to create an array with appropriate length and a mapping function to create array of grouped elements.
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- If lengths of the argument arrays vary, `undefined` is used where no value could be found.
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- The function is invoked with the elements of each group.
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```js
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const zipWith = (...array) => {
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const fn =
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typeof array[array.length - 1] === 'function' ? array.pop() : undefined;
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return Array.from({ length: Math.max(...array.map(a => a.length)) }, (_, i) =>
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fn ? fn(...array.map(a => a[i])) : array.map(a => a[i])
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);
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};
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```
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```js
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zipWith([1, 2], [10, 20], [100, 200], (a, b, c) => a + b + c); // [111, 222]
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zipWith(
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[1, 2, 3],
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[10, 20],
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[100, 200],
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(a, b, c) =>
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(a != null ? a : 'a') + (b != null ? b : 'b') + (c != null ? c : 'c')
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); // [111, 222, '3bc']
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```
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