Merge pull request #1032 from 30-seconds/add-hasKey

Add a new snippet, hasKey

snippets/hasKey.md

@@ -0,0 +1,33 @@
+---
+title: hasKey
+tags: object,recursion,intermediate
+---
+
+Returns `true` if the target value exists in a JSON object, `false` otherwise.
+
+Check if the key contains `.`, use `String.prototype.split('.')[0]` to get the first part and store as `_key`.
+Use `typeof` to check if the contents of `obj[key]` are an `object` and, if so, call `hasKey` with that object and the remainder of the `key`.
+Otherwise, use `Object.keys(obj)` in combination with `Array.prototype.includes()` to check if the given `key` exists.
+
+```js
+const hasKey = (obj, key) => {
+  if (key.includes('.')) {
+    let _key = key.split('.')[0];
+    if (typeof obj[_key] === 'object')
+      return hasKey(obj[_key], key.slice(key.indexOf('.') + 1))
+  }
+  return Object.keys(obj).includes(key);
+}
+```
+
+```js
+let obj = {
+  a: 1, b: { c: 4 }, 'd.e': 5
+}
+hasKey(obj, 'a'); // true
+hasKey(obj, 'b'); // true
+hasKey(obj, 'b.c'); // true
+hasKey(obj, 'd.e'); // true
+hasKey(obj, 'd'); // false
+hasKey(obj, 'f'); // false
+```

test/hasKey.test.js

@@ -0,0 +1,33 @@
+const {hasKey} = require('./_30s.js');
+
+const data = {
+  a: 1, b: { c: 4 }, 'd.e': 5
+};
+
+test('hasKey is a Function', () => {
+  expect(hasKey).toBeInstanceOf(Function);
+});
+
+test('hasKey returns true for simple property', () => {
+  expect(hasKey(data, 'a')).toBe(true);
+});
+
+test('hasKey returns true for object property', () => {
+  expect(hasKey(data, 'b')).toBe(true);
+});
+
+test('hasKey returns true for nested property', () => {
+  expect(hasKey(data, 'b.c')).toBe(true);
+});
+
+test('hasKey returns true for property with dots', () => {
+  expect(hasKey(data, 'd.e')).toBe(true);
+});
+
+test('hasKey returns false for non-existent property', () => {
+  expect(hasKey(data, 'f')).toBe(true);
+});
+
+test('hasKey returns false for virtual nested property', () => {
+  expect(hasKey(data, 'd')).toBe(false);
+});