Prepare repository for merge

javascript/snippets/percentile.md

@@ -0,0 +1,25 @@
+---
+title: Percentile of matches
+type: snippet
+tags: [math]
+cover: red-berries
+dateModified: 2020-10-22T20:24:04+03:00
+---
+
+Calculates the percentage of numbers in the given array that are less or equal to the given value.
+
+- Use `Array.prototype.reduce()` to calculate how many numbers are below the value and how many are the same value and apply the percentile formula.
+
+```js
+const percentile = (arr, val) =>
+  (100 *
+    arr.reduce(
+      (acc, v) => acc + (v < val ? 1 : 0) + (v === val ? 0.5 : 0),
+      0
+    )) /
+  arr.length;
+```
+
+```js
+percentile([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 6); // 55
+```