33 lines
1.3 KiB
Markdown
33 lines
1.3 KiB
Markdown
### zipWith
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Creates an array of elements, grouped based on the position in the original arrays and using function as the last value to specify how grouped values should be combined.
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Check if the last argument provided in a function.
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Use `Math.max()` to get the longest array in the arguments.
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Creates an array with that length as return value and use `Array.from()` with a map-function to create an 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 `(...group)`.
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```js
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const zipWith = (...arrays) => {
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const length = arrays.length;
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let fn = length > 1 ? arrays[length - 1] : undefined;
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fn = typeof fn == 'function' ? (arrays.pop(), fn) : undefined;
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const maxLength = Math.max(...arrays.map(x => x.length));
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const result = Array.from({ length: maxLength }).map((_, i) => {
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return Array.from({ length: arrays.length }, (_, k) => arrays[k][i]);
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});
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return fn ? result.map(arr => fn(...arr)) : result;
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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) => (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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