24 lines
949 B
Markdown
24 lines
949 B
Markdown
### zipWith
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This method is like [zip](https://30secondsofcode.org/#zip) except that it accepts a function (`fn`) as the last value to specify how grouped values should be combined.
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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([1, 2, 3], [10, 20], [100, 200], (a,b,c) => (a != null ? a : 'a') + (b != null ? b:'b') + (c != null ? c : 'c')); // [111, 222, '3bc]
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```
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