Rename js snippets

snippets/js/s/function-based-array-symmetric-difference.md

@@ -0,0 +1,27 @@
+---
+title: Array symmetric difference based on function
+type: snippet
+language: javascript
+tags: [array]
+cover: digital-nomad
+dateModified: 2020-10-18T14:58:09+03:00
+---
+
+Returns the symmetric difference between two arrays, using a provided function as a comparator.
+
+- Use `Array.prototype.filter()` and `Array.prototype.findIndex()` to find the appropriate values.
+
+```js
+const symmetricDifferenceWith = (arr, val, comp) => [
+  ...arr.filter(a => val.findIndex(b => comp(a, b)) === -1),
+  ...val.filter(a => arr.findIndex(b => comp(a, b)) === -1)
+];
+```
+
+```js
+symmetricDifferenceWith(
+  [1, 1.2, 1.5, 3, 0],
+  [1.9, 3, 0, 3.9],
+  (a, b) => Math.round(a) === Math.round(b)
+); // [1, 1.2, 3.9]
+```