fix #674: add "--platform=neutral"

CHANGELOG.md

@@ -47,6 +47,10 @@
     }
     ```
 
+* Add the `--platform=neutral` API option ([#674](https://github.com/evanw/esbuild/issues/674))
+
+    There are currently two platform values: `browser` (the default) and `node`. These settings are a convenient way to configure multiple defaults for other API options for maximum compatibility. However, some users want to configure everything themselves so esbuild does not assume any platform-specific behavior. In this case you can now use `--platform=neutral` to disable platform-specific default values. Note that this means if you want to use npm-style packages you will have to configure a main field yourself with something like `--main-fields=main`.
+
 * Provide minified and non-minified versions of in-browser API library ([#616](https://github.com/evanw/esbuild/issues/616))
 
     The in-browser JavaScript API libraries for esbuild are in the [esbuild-wasm](https://www.npmjs.com/package/esbuild-wasm) package. There are two: `esbuild-wasm/lib/browser.js` in UMD format and `esbuild-wasm/esm/browser.js` in ESM format. Previously these were minified since they contain a large string of JavaScript that cannot be minified by other tools. Now they are no longer minified, and there are new minified versions available at `esbuild-wasm/lib/browser.min.js` and `esbuild-wasm/esm/browser.min.js`.

internal/bundler/bundler.go

@@ -1789,6 +1789,8 @@ func (cache *runtimeCache) processedDefines(key config.Platform) (defines *confi
 		platform = "browser"
 	case config.PlatformNode:
 		platform = "node"
+	case config.PlatformNeutral:
+		platform = "neutral"
 	}
 	result := config.ProcessDefines(map[string]config.DefineData{
 		"__platform": {

internal/bundler/bundler_packagejson_test.go

@@ -893,3 +893,67 @@ func TestPackageJsonMainFieldsB(t *testing.T) {
 		},
 	})
 }
+
+func TestPackageJsonNeutralNoDefaultMainFields(t *testing.T) {
+	packagejson_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/entry.js": `
+				import fn from 'demo-pkg'
+				console.log(fn())
+			`,
+			"/Users/user/project/node_modules/demo-pkg/package.json": `
+				{
+					"main": "./main.js",
+					"module": "./main.esm.js"
+				}
+			`,
+			"/Users/user/project/node_modules/demo-pkg/main.js": `
+				module.exports = function() {
+					return 123
+				}
+			`,
+			"/Users/user/project/node_modules/demo-pkg/main.esm.js": `
+				export default function() {
+					return 123
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/src/entry.js"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			Platform:      config.PlatformNeutral,
+			AbsOutputFile: "/Users/user/project/out.js",
+		},
+		expectedScanLog: `Users/user/project/src/entry.js: error: Could not resolve "demo-pkg" (mark it as external to exclude it from the bundle)
+`,
+	})
+}
+
+func TestPackageJsonNeutralExplicitMainFields(t *testing.T) {
+	packagejson_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/entry.js": `
+				import fn from 'demo-pkg'
+				console.log(fn())
+			`,
+			"/Users/user/project/node_modules/demo-pkg/package.json": `
+				{
+					"hello": "./main.js",
+					"module": "./main.esm.js"
+				}
+			`,
+			"/Users/user/project/node_modules/demo-pkg/main.js": `
+				module.exports = function() {
+					return 123
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/src/entry.js"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			Platform:      config.PlatformNeutral,
+			MainFields:    []string{"hello"},
+			AbsOutputFile: "/Users/user/project/out.js",
+		},
+	})
+}

internal/bundler/snapshots/snapshots_packagejson.txt

@@ -362,3 +362,17 @@ function main_esm_default() {
 
 // Users/user/project/src/entry.js
 console.log(main_esm_default());
+
+================================================================================
+TestPackageJsonNeutralExplicitMainFields
+---------- /Users/user/project/out.js ----------
+// Users/user/project/node_modules/demo-pkg/main.js
+var require_main = __commonJS((exports, module) => {
+  module.exports = function() {
+    return 123;
+  };
+});
+
+// Users/user/project/src/entry.js
+var import_demo_pkg = __toModule(require_main());
+console.log(import_demo_pkg.default());

internal/config/config.go

@@ -27,6 +27,7 @@ type Platform uint8
 const (
 	PlatformBrowser Platform = iota
 	PlatformNode
+	PlatformNeutral
 )
 
 type StrictOptions struct {

internal/resolver/resolver.go

@@ -49,6 +49,11 @@ var defaultMainFields = map[config.Platform][]string{
 	// configure the main fields to be "module" and then "main". Keep in mind
 	// that some packages may break if you do this.
 	config.PlatformNode: []string{"main", "module"},
+
+	// The neutral platform is for people that don't want esbuild to try to
+	// pick good defaults for their platform. In that case, the list of main
+	// fields is empty by default. You must explicitly configure it yourself.
+	config.PlatformNeutral: []string{},
 }
 
 // Path resolution is a mess. One tricky issue is the "module" override for the

lib/types.ts

@@ -1,4 +1,4 @@
-export type Platform = 'browser' | 'node';
+export type Platform = 'browser' | 'node' | 'neutral';
 export type Format = 'iife' | 'cjs' | 'esm';
 export type Loader = 'js' | 'jsx' | 'ts' | 'tsx' | 'css' | 'json' | 'text' | 'base64' | 'file' | 'dataurl' | 'binary' | 'default';
 export type LogLevel = 'info' | 'warning' | 'error' | 'silent';

pkg/api/api.go

@@ -130,6 +130,7 @@ type Platform uint8
 const (
 	PlatformBrowser Platform = iota
 	PlatformNode
+	PlatformNeutral
 )
 
 type Format uint8

pkg/api/api_impl.go

@@ -35,6 +35,8 @@ func validatePlatform(value Platform) config.Platform {
 		return config.PlatformBrowser
 	case PlatformNode:
 		return config.PlatformNode
+	case PlatformNeutral:
+		return config.PlatformNeutral
 	default:
 		panic("Invalid platform")
 	}
@@ -637,6 +639,8 @@ func rebuildImpl(
 			options.OutputFormat = config.FormatIIFE
 		case config.PlatformNode:
 			options.OutputFormat = config.FormatCommonJS
+		case config.PlatformNeutral:
+			options.OutputFormat = config.FormatESModule
 		}
 	}
 

pkg/cli/cli_impl.go

@@ -290,6 +290,8 @@ func parseOptionsImpl(osArgs []string, buildOpts *api.BuildOptions, transformOpt
 				buildOpts.Platform = api.PlatformBrowser
 			case "node":
 				buildOpts.Platform = api.PlatformNode
+			case "neutral":
+				buildOpts.Platform = api.PlatformNeutral
 			default:
 				return fmt.Errorf("Invalid platform: %q (valid: browser, node)", value)
 			}