feat(book/linkedlist): linked lists techniques and common patterns

Author: amejiarosario

.eslintrc.js

@@ -1,24 +1,35 @@
 module.exports = {
   extends: 'airbnb-base',
   env: {
-    jest: true
+    jest: true,
   },
+  plugins: ['jest'],
   globals: {
     BigInt: true,
   },
+
+  // check package.json for files to include
+  // files: ['src/**/*.js', 'book/interview-questions/*.js'],
+
   rules: {
     // https://github.com/airbnb/javascript/issues/1089
 
     // https://stackoverflow.com/a/35637900/684957
     // allow to add properties to arguments
-    'no-param-reassign': [2, { 'props': false }],
+    'no-param-reassign': [2, { props: false }],
 
     // https://eslint.org/docs/rules/no-plusplus
     // allows unary operators ++ and -- in the afterthought (final expression) of a for loop.
-    'no-plusplus': [0, { 'allowForLoopAfterthoughts': true }],
+    'no-plusplus': [0, { allowForLoopAfterthoughts: true }],
     'no-continue': [0],
 
     // Allow for..of
     'no-restricted-syntax': [0, 'ForOfStatement'],
-  }
+
+    // jest plugin
+    // 'jest/no-disabled-tests': 'warn',
+    'jest/no-focused-tests': 'error',
+    'jest/no-identical-title': 'warn',
+    'jest/valid-expect': 'warn',
+  },
 };