2631. Group By

Author: donutloop

Group By/kata.js

@@ -0,0 +1,21 @@
+/**
+ * @param {Function} fn
+ * @return {Object}
+ */
+Array.prototype.groupBy = function(fn) {
+    let groups = {}
+    this.forEach((element, index) => {
+        const key = fn(element)
+        if (groups[key]) {
+            groups[key].push(element)    
+        } else {
+            groups[key] = []
+            groups[key].push(element)
+        }
+    })
+    return groups
+};
+
+/**
+ * [1,2,3].groupBy(String) // {"1":[1],"2":[2],"3":[3]}
+ */