refactor: re-implement idx (safe getter) & add test

lib/core/__tests__/utils.test.js

@@ -97,4 +97,45 @@ describe('utils', () => {
     expect(utils.getGitLastUpdated(tempFilePath)).toBeNull();
     fs.unlinkSync(tempFilePath);
   });
+
+  test('idx', () => {
+    const a = {};
+    const b = {hello: 'world'};
+    const env = {
+      translation: {
+        enabled: true,
+        enabledLanguages: [
+          {
+            enabled: true,
+            name: 'English',
+            tag: 'en',
+          },
+          {
+            enabled: true,
+            name: '日本語',
+            tag: 'ja',
+          },
+        ],
+      },
+      versioning: {
+        enabled: false,
+        versions: [],
+      },
+    };
+    const variable = 'enabledLanguages';
+    expect(utils.idx(a, [('b', 'c')])).toBeUndefined();
+    expect(utils.idx(b, ['hello'])).toEqual('world');
+    expect(utils.idx(b, 'hello')).toEqual('world');
+    expect(utils.idx(env, 'typo')).toBeUndefined();
+    expect(utils.idx(env, 'versioning')).toEqual({
+      enabled: false,
+      versions: [],
+    });
+    expect(utils.idx(env, ['translation', 'enabled'])).toEqual(true);
+    expect(
+      utils.idx(env, ['translation', variable]).map(lang => lang.tag)
+    ).toEqual(['en', 'ja']);
+    expect(utils.idx(undefined)).toBeUndefined();
+    expect(utils.idx(null)).toBeNull();
+  });
 });

lib/core/utils.js

@@ -29,8 +29,13 @@ function getPath(pathStr, cleanUrl = false) {
     : removeExtension(pathStr);
 }
 
-function idx(target, path) {
-  return path.reduce((obj, key) => obj && obj[key], target);
+function idx(target, keyPaths) {
+  return (
+    target &&
+    (Array.isArray(keyPaths)
+      ? keyPaths.reduce((obj, key) => obj && obj[key], target)
+      : target[keyPaths])
+  );
 }
 
 function getGitLastUpdated(filepath) {