Specify a minimum TypeScript version using typesVersions

Author: hsubox76

.changeset/cuddly-apes-check.md

@@ -0,0 +1,6 @@
+---
+'@firebase/app': minor
+'firebase': minor
+---
+
+Specify a minimum TypeScript version using the `typesVersions` field. Shows an error message if below.

packages/app/package.json

@@ -7,6 +7,10 @@
   "browser": "dist/esm/index.esm2017.js",
   "module": "dist/esm/index.esm2017.js",
   "react-native": "dist/index.cjs.js",
+  "typesVersions": {
+    ">=4.5.0": { "*": ["./dist/app-public.d.ts"] },
+    "<4.5.0": { "*": ["./dist/typescript-not-supported.d.ts"] }
+  },
   "exports": {
     ".": {
       "types": "./dist/app-public.d.ts",
@@ -49,6 +53,7 @@
   "devDependencies": {
     "@rollup/plugin-json": "6.1.0",
     "rollup": "2.79.2",
+    "rollup-plugin-copy": "3.5.0",
     "rollup-plugin-replace": "2.2.0",
     "rollup-plugin-typescript2": "0.36.0",
     "rollup-plugin-dts": "5.3.1",

packages/app/rollup.config.js

@@ -15,6 +15,7 @@
  * limitations under the License.
  */
 
+import copy from 'rollup-plugin-copy';
 import typescriptPlugin from 'rollup-plugin-typescript2';
 import replace from 'rollup-plugin-replace';
 import typescript from 'typescript';
@@ -53,6 +54,14 @@ const esmBuilds = [
     external: id => deps.some(dep => id === dep || id.startsWith(`${dep}/`)),
     plugins: [
       ...buildPlugins,
+      copy({
+        targets: [
+          {
+            src: './typescript-not-supported.d.ts',
+            dest: 'dist/'
+          }
+        ]
+      }),
       replace({
         ...generateBuildTargetReplaceConfig('esm', 2017),
         '__RUNTIME_ENV__': ''

packages/app/typescript-not-supported.d.ts

@@ -0,0 +1,3 @@
+// Empty typings file to log an error message for unsupported TS versions
+
+"Typescript must be version 4.5 or greater.";