Additional snippets

snippets/unique-values-of-array.md

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+### Unique values of array
+
+Use `reduce()` to accumulate all unique values in an array.
+Check if each value has already been added, using `indexOf()` on the accumulator array.
+
+```js
+var uniqueValues = arr =>
+  arr.reduce( (acc, val) => {
+    if(acc.indexOf(val) === -1)
+      acc.push(val);
+      return acc;
+  }, []);
+```