Merge pull request #689 from hszeto/dig

Dig

snippets/dig.md

@@ -0,0 +1,30 @@
+### dig
+
+Returns the target value in a nested JSON object, based on the given key.
+
+Use the `in` operator to check if `target` exists in `obj`.
+If found, return the value of `obj[target]`, otherwise use `Object.values(obj)` and `Array.reduce()` to recursively call `dig` on each nested object until the first matching key/value pair is found.
+
+```
+const dig = (obj, target) =>
+  target in obj
+    ? obj[target]
+    : Object
+        .values(obj)
+        .reduce((acc, val) => {
+          if (acc !== undefined) return acc;
+          if (typeof val === 'object') return dig(val, target);
+        }, undefined);
+```
+
+```
+const data = {
+  level1:{
+    level2:{
+      level3: 'some data'
+    }
+  }
+};
+dig(data, 'level3'); // 'some data'
+dig(data, 'level4'); // undefined
+```

tag_database

@@ -55,6 +55,7 @@ detectDeviceType:browser
 difference:array,math
 differenceBy:array,function
 differenceWith:array,function
+dig:object,recursion
 digitize:math,array
 distance:math
 drop:array

test/dig/dig.js

@@ -0,0 +1,15 @@
+const dig = (obj, target) =>
+  target in obj
+    ? obj[target]
+    : Object
+        .values(obj)
+        .reduce((acc, val) => {
+          if (acc !== undefined) {
+            return acc;
+          }
+          if (typeof val === "object") {
+            return dig(val, target);
+          }
+        }, undefined);
+
+module.exports = dig;

test/dig/dig.test.js

@@ -0,0 +1,32 @@
+const expect = require("expect");
+const dig = require("./dig.js");
+
+const data = {
+  level1:{
+    level2:{
+      level3: "some data",
+      level3f: false,
+      level3a: [1,2,3,4]
+    }
+  }
+};
+
+test("dig is a Function", () => {
+  expect(dig).toBeInstanceOf(Function);
+});
+
+test("Dig target success", () => {
+  expect(dig(data, "level3")).toEqual("some data");
+});
+
+test("Dig target with falsey value", () => {
+  expect(dig(data, "level3f")).toEqual(false);
+});
+
+test("Dig target with array", () => {
+  expect(dig(data, "level3a")).toEqual([1,2,3,4]);
+});
+
+test("Unknown target return undefined", () => {
+  expect(dig(data, "level4")).toEqual(undefined);
+});