Add check to make sure newly compiled dts versions work in downstream projects with older typescript versions

.github/workflows/validate-dts-against-old-typescript.yaml

@@ -0,0 +1,25 @@
+name: 'validate-dts-against-old-typescript'
+permissions:
+  contents: read
+on:
+  pull_request:
+    branches:
+      - main
+  workflow_dispatch:
+jobs:
+  validate-dts-against-old-typescript:
+    runs-on: ubuntu-latest
+    env:
+      CI_JOB_NUMBER: 1
+    steps:
+      - uses: actions/checkout@v5
+      - uses: pnpm/action-setup@v4
+      - name: Use Node.js 24
+        uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: 'pnpm'
+      - name: Install dependencies
+        run: pnpm install
+      - name: Validates that livekit-client can be parsed in a typescript 4.8 project
+        run: pnpm validate-dts-against-old-typescript 4.8

.gitignore

@@ -113,4 +113,7 @@ pkg/
 bin/
 examples/**/build/
 
-.env.local
+# dts validation task working directory
+dts-validation/
+
+.env.local

package.json

@@ -51,6 +51,7 @@
     "format:check": "prettier --check src examples/**/*.ts",
     "ci:publish": "pnpm build:clean && pnpm compat && changeset publish",
     "downlevel-dts": "downlevel-dts ./dist/src ./dist/ts4.2 --to=4.2",
+    "validate-dts-against-old-typescript": "./validate-dts-against-old-typescript.sh",
     "compat": "eslint --config ./eslint.config.dist.mjs --no-inline-config  ./dist/livekit-client.esm.mjs",
     "size-limit": "size-limit"
   },

validate-dts-against-old-typescript.sh

@@ -0,0 +1,68 @@
+#!/bin/bash
+# Runs a check to make sure that a given version of livekit-client can be used in a downstream project
+# which is configured with an older version typescript.
+#
+# In theory, downlevel-dts should handle this, but there has been at least one breaking typing
+# change in the past which downlevel-dts has been unable to patch over
+# (more info: https://github.com/livekit/client-sdk-js/pull/1668) so this serves as a mechanism to
+# catch cases like this in the future before they are reported by users.
+
+TYPESCRIPT_VERSION=${1:-"4.8"}
+
+echo "# Performing clean build of livekit-client library..."
+pnpm build:clean
+
+echo "# Instantiating dts-validation working directory..."
+rm -rf dts-validation
+mkdir dts-validation
+cd dts-validation
+
+pnpm init
+pnpm install typescript@${TYPESCRIPT_VERSION}
+pnpm install ../
+
+echo "import 'livekit-client';" > index.ts
+cat <<EOF > tsconfig.json
+{
+  "compilerOptions": {
+    "types": ["sdp-transform", "ua-parser-js", "events", "dom-mediacapture-record"],
+    "target": "ES2015" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */,
+    "module": "ES2020" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */,
+    "lib": [
+      "DOM",
+      "DOM.Iterable",
+      "ES2017",
+      "ES2018.Promise",
+      "ES2018.AsyncGenerator",
+      "ES2020.BigInt",
+      "ES2021.WeakRef",
+      "ESNext.AsyncIterable"
+    ],
+    "rootDir": "./",
+    "outDir": "dist",
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true,
+    "strict": true /* Enable all strict type-checking options. */,
+    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
+    "skipLibCheck": false /* Skip type checking of declaration files. */,
+    "noUnusedLocals": true,
+    "forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */,
+    "moduleResolution": "node",
+    "resolveJsonModule": true
+  },
+  "include": ["index.ts"]
+}
+EOF
+
+echo "# Running tsc against dts-validation working directory..."
+npx tsc
+result="$?"
+
+if [[ "${result}" -eq "0" ]]; then
+  echo "# tsc ran successfully against demo typescript ${TYPESCRIPT_VERSION} project, PASS!"
+else
+  echo "# tsc errored when ran against demo typescript ${TYPESCRIPT_VERSION} project, FAIL!"
+fi
+
+exit ${result}