Add findKey, findLastKey

snippets/findKey.md

@@ -0,0 +1,14 @@
+### findKey
+
+Returns the first key that satisfies the provided testing function. Otherwise `undefined` is returned.
+
+Use `Object.keys(obj)` to get all the properties of the object, `Array.find()` to test the provided function for each key-value pair. The callback receives three arguments - the value, the key and the object.
+
+```js
+const findKey = (obj, fn) =>
+  Object.keys(obj).find(key => fn(obj[key], key, obj));
+```
+
+```js
+findKey({barney: { age: 36, active: true }, fred: { age: 40, active: false }, pebbles: { age: 1, active: true }}, o => o['active']); // 'barney'
+```

snippets/findLastKey.md

@@ -0,0 +1,14 @@
+### findLastKey
+
+Returns the last key that satisfies the provided testing function. Otherwise `undefined` is returned.
+
+Use `Object.keys(obj)` to get all the properties of the object, `Array.reverse()` to reverse their order and `Array.find()` to test the provided function for each key-value pair. The callback receives three arguments - the value, the key and the object.
+
+```js
+const findLastKey = (obj, fn) =>
+  Object.keys(obj).reverse().find(key => fn(obj[key], key, obj));
+```
+
+```js
+findKey({barney: { age: 36, active: true }, fred: { age: 40, active: false }, pebbles: { age: 1, active: true }}, o => o['active']); // 'pebbles'
+```

tag_database

@@ -47,7 +47,9 @@ extendHex:utility,string
 factorial:math,recursion
 fibonacci:math,array
 filterNonUnique:array
+findKey:object,function
 findLast:array
+findLastKey:object,function
 flatten:array
 flip:adapter,function
 forEachRight:array,function