28 lines
1.3 KiB
Markdown
28 lines
1.3 KiB
Markdown
### zipWith
|
||
|
||
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.
|
||
|
||
Check if the last argument provided in a function.
|
||
Use `Math.max()` to get the longest array in the arguments.
|
||
Creates an array with that length as return value and use `Array.from()` with a map-function to create an array of grouped elements.
|
||
If lengths of the argument-arrays vary, `undefined` is used where no value could be found.
|
||
The function is invoked with the elements of each group `(...group)`.
|
||
|
||
``` js
|
||
const zipWith = (...arrays) => {
|
||
const length = arrays.length;
|
||
let fn = length > 1 ? arrays[length - 1] : undefined;
|
||
fn = typeof fn == 'function' ? (arrays.pop(), fn) : undefined;
|
||
const maxLength = Math.max(...arrays.map(x => x.length));
|
||
const result = Array.from({ length: maxLength }).map((_, i) => {
|
||
return Array.from({ length: arrays.length }, (_, k) => arrays[k][i]);
|
||
})
|
||
return fn ? result.map(arr => fn(...arr)) : result;
|
||
}
|
||
```
|
||
|
||
``` js
|
||
zipWith([1, 2], [10, 20], [100, 200], (a,b,c) => a + b + c); // [111,222]
|
||
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']
|
||
```
|