Given a Collection and a search value, find the index of closet matching value, rounding UP

collection-search-find-index-between.js

/**
<p>Given a collection (array of objects) and a value, find the index of the closest matching value (rounding UP).</p>
<br/>

<strong.=>example:</strong>
<pre>
var arr = [{ val: 0}, { val: 25}, { val: 50}, { val: 75}, { val: 100}];

Given: 0    // given value to find
Expected: 0 //index

Given: 26
Expected: 2   // using val: 50 as the match

Given: 50
Expected: 2

Given: 74
Expected: 3

</pre>
**/
import { map } from 'lodash';

const arr = [{ val: 0}, { val: 25}, { val: 50}, { val: 75}, { val: 100}];

const findClosestIndex = (collection, searchVal, key = 'value') => (
  map(collection, key).reduce((prev, cur, index) => (
    (searchVal <= cur && prev == null) ? index : prev
    ), null)
);

console.log(0, ' is closest to index ', findClosestIndex(arr, 0, 'val'));

console.log(26, ' is closest to index ', findClosestIndex(arr, 26, 'val'));

console.log(50, ' is closest to index ', findClosestIndex(arr, 50, 'val'));

console.log(74, ' is closest to index ', findClosestIndex(arr, 74, 'val'));

console.log(99, ' is closest to index ', findClosestIndex(arr, 99, 'val'));