diff --git a/.github/workflows/node.js.yml b/.github/workflows/node.js.yml
new file mode 100644
index 0000000..a327bf2
--- /dev/null
+++ b/.github/workflows/node.js.yml
@@ -0,0 +1,29 @@
+# This workflow will do a clean installation of node dependencies, cache/restore them, build the source code and run tests across different versions of node
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-nodejs-with-github-actions
+
+name: Node.js CI
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [16.x]
+        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v3
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: yarn
+    - run: yarn test
diff --git a/lib/add.js b/lib/add.js
index 1714b95..74f064e 100644
--- a/lib/add.js
+++ b/lib/add.js
@@ -1,5 +1,15 @@
-function add() {
+function add(num1, num2) {
   // 实现该函数
+  let len1 = num1.length;
+  let len2 = num2.length;
+  let sum = '';
+  let carry = 0;
+  while(len1 || len2 || carry) {
+    let cur = (len1 ? Number(num1.charAt(--len1)) : 0) + (len2 ? Number(num2.charAt(--len2)) : 0) + carry;
+    sum = cur % 10 + sum;
+    carry = Math.floor(cur / 10);
+  }
+  return sum;
 }
 
 module.exports = add
\ No newline at end of file