20 lines
699 B
Markdown
20 lines
699 B
Markdown
### sortedIndexBy
|
|
|
|
Returns the lowest index at which value should be inserted into array in order to maintain its sort order, based on a provided iterator function.
|
|
|
|
Check if the array is sorted in descending order (loosely).
|
|
Use `Array.findIndex()` to find the appropriate index where the element should be inserted, based on the iterator function `fn`.
|
|
|
|
```js
|
|
const sortedIndexBy = (arr, n, fn) => {
|
|
const isDescending = fn(arr[0]) > fn(arr[arr.length - 1]);
|
|
const val = fn(n);
|
|
const index = arr.findIndex(el => (isDescending ? val >= fn(el) : val <= fn(el)));
|
|
return index === -1 ? arr.length : index;
|
|
};
|
|
```
|
|
|
|
```js
|
|
sortedIndexBy([{ 'x': 4 }, { 'x': 5 }], { 'x': 4 }, o => o.x); // 0
|
|
```
|