BREAKING: Drop Node.js 14/16 support, require Node.js >=18 (#1747)

* BREAKING: Drop Node.js 14/16 support, require Node.js >=18

- Update package.json engines to require Node.js >=18.0.0
- Upgrade @types/node from v14 to v18
- Update TypeScript target from ES2019 to ES2022
- Add useDefineForClassFields: false for backward compatibility
- Update CI/CD workflows to test Node.js 18, 20, 22, and 24
- Set default CI/CD Node.js version to 24
- Update integration test documentation

Author: taeold

.github/workflows/docs.yaml

@@ -12,7 +12,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: "20"
+          node-version: "24"
       - name: Cache npm
         uses: actions/cache@v4
         with:

.github/workflows/postmerge.yaml

@@ -30,7 +30,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
         with:
-          node-version: 18
+          node-version: 24
 
       - uses: google-github-actions/auth@v0
         with:

.github/workflows/test.yaml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       matrix:
         node-version:
-          - 18.x
+          - 24.x
     steps:
       - uses: actions/checkout@v3
         with:
@@ -33,6 +33,7 @@ jobs:
           - 18.x
           - 20.x
           - 22.x
+          - 24.x
     steps:
       - uses: actions/checkout@v1
       - uses: actions/setup-node@v1
@@ -54,6 +55,7 @@ jobs:
           - 18.x
           - 20.x
           - 22.x
+          - 24.x
     steps:
       - uses: actions/checkout@v1
       - uses: actions/setup-node@v1

package-lock.json

@@ -286,7 +286,7 @@
     "@types/mocha": "^5.2.7",
     "@types/mock-require": "^2.0.0",
     "@types/nock": "^10.0.3",
-    "@types/node": "^14.18.24",
+    "@types/node": "^18.0.0",
     "@types/node-fetch": "^3.0.3",
     "@types/sinon": "^9.0.11",
     "@typescript-eslint/eslint-plugin": "^5.33.1",
@@ -324,6 +324,6 @@
     "firebase-admin": "^11.10.0 || ^12.0.0 || ^13.0.0"
   },
   "engines": {
-    "node": ">=14.10.0"
+    "node": ">=18.0.0"
   }
 }

package.json

@@ -1,13 +1,14 @@
 {
   "compilerOptions": {
     "declaration": true,
-    "lib": ["es2019"],
+    "lib": ["es2022"],
     "module": "commonjs",
     "noImplicitAny": false,
     "noUnusedLocals": true,
     "outDir": "lib",
     "stripInternal": true,
-    "target": "es2019",
+    "target": "es2022",
+    "useDefineForClassFields": false,
     "typeRoots": ["./node_modules/@types"]
   },
   "files": [