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javascript/snippets/common-keys.md

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+---
+title: Common keys
+type: snippet
+tags: [object]
+author: chalarangelo
+cover: symmetry-cloudy-mountain
+dateModified: 2022-04-23T05:00:00-04:00
+---
+
+Finds the common keys between two objects.
+
+- Use `Object.keys()` to get the keys of the first object.
+- Use `Object.prototype.hasOwnProperty()` to check if the second object has a key that's in the first object.
+- Use `Array.prototype.filter()` to filter out keys that aren't in both objects.
+
+```js
+const commonKeys = (obj1, obj2) =>
+  Object.keys(obj1).filter(key => obj2.hasOwnProperty(key));
+```
+
+```js
+commonKeys({ a: 1, b: 2 }, { a: 2, c: 1 }); // ['a']
+```