js: Pass tsconfig.json to esBuild

Note that esBuild only inspects/honors certain fields.
See https://esbuild.github.io/content-types/#tsconfig-json.

Fixes #11232

resources/resource_transformers/js/build.go

@@ -86,6 +86,7 @@ func (t *buildTransformation) Transform(ctx *resources.ResourceTransformationCtx
 	opts.resolveDir = t.c.rs.Cfg.BaseConfig().WorkingDir // where node_modules gets resolved
 	opts.contents = string(src)
 	opts.mediaType = ctx.InMediaType
+	opts.tsConfig = t.c.rs.ResolveJSConfigFile("tsconfig.json")
 
 	buildOptions, err := toBuildOptions(opts)
 	if err != nil {

resources/resource_transformers/js/integration_test.go

@@ -344,3 +344,32 @@ Main license
 	`)
 
 }
+
+// Issue #11232
+func TestTypeScriptExperimentalDecorators(t *testing.T) {
+	t.Parallel()
+	files := `
+-- hugo.toml --
+disableKinds = ['RSS','sitemap','taxonomy','term']
+-- tsconfig.json --
+{
+  "compilerOptions": {
+    "experimentalDecorators": true,
+  }
+}
+-- assets/ts/main.ts --
+function addFoo(target: any) {target.prototype.foo = 'bar'}
+@addFoo
+class A {}
+-- layouts/index.html --
+{{ $opts := dict "target" "es2020" "targetPath" "js/main.js" }}
+{{ (resources.Get "ts/main.ts" | js.Build $opts).Publish }}
+`
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			NeedsOsFS:   true,
+			TxtarString: files,
+		}).Build()
+	b.AssertFileContent("public/js/main.js", "__decorateClass")
+}