fix #2798: make type declarations work in TS v3.5+

.github/workflows/ci.yml

@@ -163,7 +163,7 @@ jobs:
         run: cd scripts && node gen-unicode-table.js
 
   esbuild-old-golang:
-    name: esbuild CI (old Go version)
+    name: esbuild CI (old versions)
     runs-on: ubuntu-latest
 
     steps:
@@ -181,3 +181,6 @@ jobs:
 
       - name: go test
         run: go test ./internal/...
+
+      - name: make test-old-ts
+        run: make test-old-ts

CHANGELOG.md

@@ -26,6 +26,20 @@
     export * from "./b"
     ```
 
+* Remove new type syntax from type declarations in the `esbuild` package ([#2798](https://github.com/evanw/esbuild/issues/2798))
+
+    Previously you needed to use TypeScript 4.3 or newer when using the `esbuild` package from TypeScript code due to the use of a getter in an interface in `node_modules/esbuild/lib/main.d.ts`. This release removes this newer syntax to allow people with versions of TypeScript as far back as TypeScript 3.5 to use this latest version of the `esbuild` package. Here is change that was made to esbuild's type declarations:
+
+    ```diff
+     export interface OutputFile {
+       /** "text" as bytes */
+       contents: Uint8Array;
+       /** "contents" as text (changes automatically with "contents") */
+    -  get text(): string;
+    +  readonly text: string;
+     }
+    ```
+
 ## 0.16.14
 
 * Preserve some comments in expressions ([#2721](https://github.com/evanw/esbuild/issues/2721))

Makefile

@@ -94,6 +94,15 @@ plugin-tests: version-go
 ts-type-tests: | scripts/node_modules
 	node scripts/ts-type-tests.js
 
+require/old-ts/node_modules:
+	cd require/old-ts && npm ci
+
+test-old-ts: platform-neutral | require/old-ts/node_modules
+	rm -fr scripts/.test-old-ts && mkdir scripts/.test-old-ts
+	cp `find npm/esbuild -name '*.d.ts'` scripts/.test-old-ts
+	cd scripts/.test-old-ts && ../../require/old-ts/node_modules/.bin/tsc *.d.ts
+	rm -fr scripts/.test-old-ts
+
 node-unref-tests: | scripts/node_modules
 	node scripts/node-unref-tests.js
 

lib/shared/types.ts

@@ -196,7 +196,7 @@ export interface OutputFile {
   /** "text" as bytes */
   contents: Uint8Array;
   /** "contents" as text (changes automatically with "contents") */
-  get text(): string;
+  readonly text: string;
 }
 
 export interface BuildInvalidate {

require/old-ts/README.md

@@ -0,0 +1,3 @@
+# Old TypeScript version
+
+This is used to ensure that our type definitions don't accidentally use newer features that break in older versions of TypeScript.

require/old-ts/package.json

@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "typescript": "3.5.3"
+  }
+}