new message when "type" should be "types" (#395)

Author: evanw

internal/bundler/bundler_packagejson_test.go

@@ -2348,3 +2348,26 @@ NOTE: You can mark the path "foo" as external to exclude it from the bundle, whi
 `,
 	})
 }
+
+func TestPackageJsonTypeShouldBeTypes(t *testing.T) {
+	packagejson_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/index.js": ``,
+			"/Users/user/project/package.json": `
+				{
+					"main": "./src/index.js",
+					"type": "./src/index.d.ts"
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/src/index.js"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+			MainFields:    []string{},
+		},
+		expectedScanLog: `Users/user/project/package.json: WARNING: "./src/index.d.ts" is not a valid value for the "type" field
+Users/user/project/package.json: NOTE: TypeScript type declarations use the "types" field, not the "type" field:
+`,
+	})
+}

internal/bundler/snapshots/snapshots_packagejson.txt

@@ -697,3 +697,7 @@ var require_main = __commonJS({
 // Users/user/project/src/entry.js
 var import_demo_pkg = __toESM(require_main());
 console.log((0, import_demo_pkg.default)());
+
+================================================================================
+TestPackageJsonTypeShouldBeTypes
+---------- /Users/user/project/out.js ----------

internal/resolver/package_json.go

@@ -260,7 +260,7 @@ func (r resolverQuery) parsePackageJSON(inputPath string) *packageJSON {
 	}
 
 	// Read the "type" field
-	if typeJSON, _, ok := getProperty(json, "type"); ok {
+	if typeJSON, typeKeyLoc, ok := getProperty(json, "type"); ok {
 		if typeValue, ok := getString(typeJSON); ok {
 			switch typeValue {
 			case "commonjs":
@@ -276,10 +276,24 @@ func (r resolverQuery) parsePackageJSON(inputPath string) *packageJSON {
 					Range:  jsonSource.RangeOfString(typeJSON.Loc),
 				}
 			default:
-				r.log.AddWithNotes(logger.Warning, &tracker, jsonSource.RangeOfString(typeJSON.Loc),
+				notes := []logger.MsgData{{Text: "The \"type\" field must be set to either \"commonjs\" or \"module\"."}}
+				kind := logger.Warning
+
+				// If someone does something like "type": "./index.d.ts" then they
+				// likely meant "types" instead of "type". Customize the message
+				// for this and hide it if it's inside a published npm package.
+				if strings.HasSuffix(typeValue, ".d.ts") {
+					notes[0] = tracker.MsgData(jsonSource.RangeOfString(typeKeyLoc),
+						"TypeScript type declarations use the \"types\" field, not the \"type\" field:")
+					notes[0].Location.Suggestion = "\"types\""
+					if helpers.IsInsideNodeModules(jsonSource.KeyPath.Text) {
+						kind = logger.Debug
+					}
+				}
+
+				r.log.AddWithNotes(kind, &tracker, jsonSource.RangeOfString(typeJSON.Loc),
 					fmt.Sprintf("%q is not a valid value for the \"type\" field", typeValue),
-					[]logger.MsgData{{Text: "The \"type\" field must be set to either \"commonjs\" or \"module\"."}},
-				)
+					notes)
 			}
 		} else {
 			r.log.Add(logger.Warning, &tracker, logger.Range{Loc: typeJSON.Loc},