Create findKeys.md

snippets/findKeys.md

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+---
+title: findKeys
+tags: object,beginner
+---
+
+Return all the keys in the provided object that match the given value.
+
+- Use `Object.keys(object)` to get all the properties of the object.
+- Use `Array.prototype.filter()` to test each key-value pair and return all keys that equal to the given value.
+
+
+```js
+const findKeys = (object, value) =>
+  Object.keys(object).filter(key => object[key] === value);
+```
+
+```js
+const ages = {
+  "Leo" : 20,
+  "Zoey" : 21,
+  "Jane" : 20
+};
+
+findKeys(ages, 20); // [ "Leo", "Jane" ]
+```