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javascript/snippets/symmetric-difference.md

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+---
+title: Array symmetric difference
+type: snippet
+tags: [array,math]
+cover: trippy-chemicals
+dateModified: 2020-10-22T20:24:30+03:00
+---
+
+Returns the symmetric difference between two arrays, without filtering out duplicate values.
+
+- Create a `Set` from each array to get the unique values of each one.
+- Use `Array.prototype.filter()` on each of them to only keep values not contained in the other.
+
+```js
+const symmetricDifference = (a, b) => {
+  const sA = new Set(a),
+    sB = new Set(b);
+  return [...a.filter(x => !sB.has(x)), ...b.filter(x => !sA.has(x))];
+};
+```
+
+```js
+symmetricDifference([1, 2, 3], [1, 2, 4]); // [3, 4]
+symmetricDifference([1, 2, 2], [1, 3, 1]); // [2, 2, 3]
+```