chore: set up TypeScript

.babelrc

@@ -1,5 +1,5 @@
 {
-  "presets": ["@babel/preset-env"],
+  "presets": ["@babel/preset-env", "@babel/preset-typescript"],
   "plugins": [
     [
       "babel-plugin-transform-builtin-extend",

.eslintignore

@@ -1 +1,4 @@
 coverage
+
+# TypeScript compiled files
+lib

.eslintrc.js

@@ -1,16 +1,30 @@
 module.exports = {
-  extends: ['airbnb-base', 'prettier'],
+  extends: [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/eslint-recommended',
+    'plugin:@typescript-eslint/recommended',
+    'airbnb-base',
+    'prettier',
+  ],
   env: {
     browser: true,
     jest: true,
     node: true,
   },
-  plugins: ['prettier'],
+  parser: '@typescript-eslint/parser',
+  plugins: ['@typescript-eslint', 'prettier'],
   rules: {
     'no-param-reassign': 'off', // Needed for swapping elements within an array.
     'no-plusplus': 'off',
     'no-underscore-dangle': 'off', // Indicate private methods.
     'no-unused-vars': ['error', { argsIgnorePattern: '^_$' }], // Ignore variables called _.
     'prettier/prettier': 'error',
   },
+  settings: {
+    'import/resolver': {
+      node: {
+        extensions: ['.js', '.ts'],
+      },
+    },
+  },
 };

.gitignore

@@ -57,3 +57,5 @@ typings/
 # dotenv environment variables file
 .env
 
+# TypeScript compiles files
+lib

.prettierignore

@@ -0,0 +1,2 @@
+# TypeScript compiled files
+lib

package.json

@@ -7,8 +7,8 @@
     "check-all": "yarn prettier && yarn lint && yarn test",
     "check-all:ci": "yarn prettier && yarn lint && yarn run test:ci",
     "lint": "eslint .",
-    "prettier": "prettier --config .prettierrc --write 'src/**/*.js'",
-    "prettier:diff": "prettier --config .prettierrc --list-different 'src/**/*.js'",
+    "prettier": "prettier --config .prettierrc --write 'src/**/*.{js,ts}'",
+    "prettier:diff": "prettier --config .prettierrc --list-different 'src/**/*.{js,ts}'",
     "test": "jest --coverage",
     "test:ci": "jest --coverage --runInBand",
     "start": "jest --coverage --watch"
@@ -27,6 +27,9 @@
   "homepage": "https://github.com/yangshun/lago#readme",
   "devDependencies": {
     "@babel/preset-env": "^7.10.4",
+    "@babel/preset-typescript": "^7.10.4",
+    "@typescript-eslint/eslint-plugin": "^3.5.0",
+    "@typescript-eslint/parser": "^3.5.0",
     "babel-jest": "^26.1.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "eslint": "^7.4.0",
@@ -36,6 +39,7 @@
     "eslint-plugin-prettier": "^3.1.4",
     "jest": "^26.1.0",
     "lodash": "^4.17.4",
-    "prettier": "^2.0.5"
+    "prettier": "^2.0.5",
+    "typescript": "^3.9.6"
   }
 }

src/algorithms/__tests__/breadthFirstSearch.test.js

@@ -6,79 +6,90 @@ describe('breadthFirstSearch', () => {
   });
 
   test('graphs with one node', () => {
-    expect(breadthFirstSearch({ '1': [] }, '1')).toEqual(['1']);
-    expect(breadthFirstSearch({ '1': ['1'] }, '1')).toEqual(['1']);
+    expect(breadthFirstSearch({ 1: [] }, '1')).toEqual(['1']);
+    expect(breadthFirstSearch({ 1: ['1'] }, '1')).toEqual(['1']);
   });
 
   test('graphs with two nodes', () => {
-    expect(breadthFirstSearch({ '1': ['2'], '2': [] }, '1')).toEqual([
+    expect(breadthFirstSearch({ 1: ['2'], 2: [] }, '1')).toEqual(['1', '2']);
+    expect(breadthFirstSearch({ 1: ['1', '2'], 2: [] }, '1')).toEqual([
       '1',
       '2',
     ]);
-    expect(breadthFirstSearch({ '1': ['1', '2'], '2': [] }, '1')).toEqual([
-      '1',
-      '2',
-    ]);
-    expect(breadthFirstSearch({ '1': ['1', '2'], '2': [] }, '2')).toEqual([
-      '2',
-    ]);
-    expect(breadthFirstSearch({ '1': ['1', '2'], '2': ['1'] }, '2')).toEqual([
+    expect(breadthFirstSearch({ 1: ['1', '2'], 2: [] }, '2')).toEqual(['2']);
+    expect(breadthFirstSearch({ 1: ['1', '2'], 2: ['1'] }, '2')).toEqual([
       '2',
       '1',
     ]);
   });
 
   test('graphs with multiple nodes', () => {
-    expect(
-      breadthFirstSearch({ '1': ['2'], '2': ['3'], '3': [] }, '1'),
-    ).toEqual(['1', '2', '3']);
-    expect(
-      breadthFirstSearch({ '1': ['2', '3'], '2': [], '3': [] }, '1'),
-    ).toEqual(['1', '2', '3']);
+    expect(breadthFirstSearch({ 1: ['2'], 2: ['3'], 3: [] }, '1')).toEqual([
+      '1',
+      '2',
+      '3',
+    ]);
+    expect(breadthFirstSearch({ 1: ['2', '3'], 2: [], 3: [] }, '1')).toEqual([
+      '1',
+      '2',
+      '3',
+    ]);
     expect(
       breadthFirstSearch(
-        { '1': ['2', '3'], '2': [], '3': [], '4': ['2'], '5': ['3'] },
+        {
+          1: ['2', '3'],
+          2: [],
+          3: [],
+          4: ['2'],
+          5: ['3'],
+        },
         '1',
       ),
     ).toEqual(['1', '2', '3']);
     expect(
       breadthFirstSearch(
-        { '1': ['4', '5'], '2': [], '3': [], '4': ['2'], '5': ['3'] },
+        {
+          1: ['4', '5'],
+          2: [],
+          3: [],
+          4: ['2'],
+          5: ['3'],
+        },
         '1',
       ),
     ).toEqual(['1', '4', '5', '2', '3']);
     expect(
       breadthFirstSearch(
         {
-          '1': ['4', '5'],
-          '2': ['1', '2', '3', '4', '5'],
-          '3': [],
-          '4': ['2'],
-          '5': ['3'],
+          1: ['4', '5'],
+          2: ['1', '2', '3', '4', '5'],
+          3: [],
+          4: ['2'],
+          5: ['3'],
         },
         '1',
       ),
     ).toEqual(['1', '4', '5', '2', '3']);
     expect(
       breadthFirstSearch(
         {
-          '1': ['1', '2', '3', '4', '5'],
-          '2': [],
-          '3': [],
-          '4': ['2'],
-          '5': ['3'],
+          1: ['1', '2', '3', '4', '5'],
+          2: [],
+          3: [],
+          4: ['2'],
+          5: ['3'],
         },
         '1',
       ),
     ).toEqual(['1', '2', '3', '4', '5']);
     // Graph taken from https://www.geeksforgeeks.org/breadth-first-traversal-for-a-graph/
     const graph = {
-      '1': ['2', '3'],
-      '2': ['1', '4', '5'],
-      '3': ['1', '5'],
-      '4': ['2', '5', '6'],
-      '5': ['2', '3', '4', '6'],
-      '6': ['4', '5'],
+      1: ['2', '3'],
+      2: ['1', '4', '5'],
+      3: ['1', '5'],
+      4: ['2', '5', '6'],
+      5: ['2', '3', '4', '6'],
+      6: ['4', '5'],
     };
     expect(breadthFirstSearch(graph, '1')).toEqual([
       '1',
@@ -132,13 +143,37 @@ describe('breadthFirstSearch', () => {
 
   test('disjoint graphs', () => {
     expect(
-      breadthFirstSearch({ '1': ['2'], '2': [], '3': [], '4': ['3'] }, '1'),
+      breadthFirstSearch(
+        {
+          1: ['2'],
+          2: [],
+          3: [],
+          4: ['3'],
+        },
+        '1',
+      ),
     ).toEqual(['1', '2']);
     expect(
-      breadthFirstSearch({ '1': ['2'], '2': [], '3': [], '4': ['3'] }, '3'),
+      breadthFirstSearch(
+        {
+          1: ['2'],
+          2: [],
+          3: [],
+          4: ['3'],
+        },
+        '3',
+      ),
     ).toEqual(['3']);
     expect(
-      breadthFirstSearch({ '1': ['2'], '2': [], '3': [], '4': ['3'] }, '4'),
+      breadthFirstSearch(
+        {
+          1: ['2'],
+          2: [],
+          3: [],
+          4: ['3'],
+        },
+        '4',
+      ),
     ).toEqual(['4', '3']);
   });
 });