fix #334: support automatic JSX runtime

CHANGELOG.md

@@ -1,5 +1,60 @@
 # Changelog
 
+## Unreleased
+
+* Add support for React 17's `automatic` JSX transform ([#334](https://github.com/evanw/esbuild/issues/334), [#718](https://github.com/evanw/esbuild/issues/718), [#1172](https://github.com/evanw/esbuild/issues/1172), [#2318](https://github.com/evanw/esbuild/issues/2318), [#334](https://github.com/evanw/esbuild/pull/2349))
+
+    This adds support for the [new "automatic" JSX runtime from React 17+](https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html) to esbuild for both the build and transform APIs.
+
+    **New CLI flags and API options:**
+    - `--jsx`, `jsx` — Set this to `"automatic"` to opt in to this new transform
+    - `--jsx-dev`, `jsxDev` — Toggles development mode for the automatic runtime
+    - `--jsx-import-source`, `jsxImportSource` — Overrides the root import for runtime functions (default `"react"`)
+
+    **New JSX pragma comments:**
+    - `@jsxRuntime` — Sets the runtime (`automatic` or `classic`)
+    - `@jsxImportSource` — Sets the import source (only valid with automatic runtime)
+
+    The existing `@jsxFragment` and `@jsxFactory` pragma comments are only valid with "classic" runtime.
+
+    **TSConfig resolving:**
+    Along with accepting the new options directly via CLI or API, option inference from `tsconfig.json` compiler options was also implemented:
+
+    - `"jsx": "preserve"` or `"jsx": "react-native"` → Same as `--jsx=preserve` in esbuild
+    - `"jsx": "react"` → Same as `--jsx=transform` in esbuild (which is the default behavior)
+    - `"jsx": "react-jsx"` → Same as `--jsx=automatic` in esbuild
+    - `"jsx": "react-jsxdev"` → Same as `--jsx=automatic --jsx-dev` in esbuild
+
+    It also reads the value of `"jsxImportSource"` from `tsconfig.json` if specified.
+
+    For `react-jsx` it's important to note that it doesn't implicitly disable `--jsx-dev`. This is to support the case where a user sets `"react-jsx"` in their `tsconfig.json` but then toggles development mode directly in esbuild.
+
+    **esbuild vs Babel vs TS vs...**
+
+    There are a few differences between the various technologies that implement automatic JSX runtimes. The JSX transform in esbuild follows a mix of Babel's and TypeScript's behavior:
+
+    - When an element has `__source` or `__self` props:
+        - Babel: Print an error about a deprecated transform plugin
+        - TypeScript: Allow the props
+        - swc: Hard crash
+        - **esbuild**: Print an error — Following Babel was chosen for this one because this might help people catch configuration issues where JSX files are being parsed by multiple tools
+
+    - Element has an "implicit true" key prop, e.g. `<a key />`:
+        - Babel: Print an error indicating that "key" props require an explicit value
+        - TypeScript: Silently omit the "key" prop
+        - swc: Hard crash
+        - **esbuild**: Print an error like Babel &mdash; This might help catch legitimate programming mistakes
+
+    - Element has spread children, e.g. `<a>{...children}</a>`
+        - Babel: Print an error stating that React doesn't support spread children
+        - TypeScript: Use static jsx function and pass children as-is, including spread operator
+        - swc: same as Babel
+        - **esbuild**: Same as TypeScript
+
+    Also note that TypeScript has some bugs regarding JSX development mode and the generation of `lineNumber` and `columnNumber` values. Babel's values are accurate though, so esbuild's line and column numbers match Babel. Both numbers are 1-based and columns are counted in terms of UTF-16 code units.
+
+    This feature was contributed by [@jgoz](https://github.com/jgoz).
+
 ## 0.14.50
 
 * Emit `names` in source maps ([#1296](https://github.com/evanw/esbuild/issues/1296))

cmd/esbuild/main.go

@@ -77,9 +77,13 @@ var helpText = func(colors logger.Colors) string {
                             incorrect tree-shaking annotations
   --inject:F                Import the file F into all input files and
                             automatically replace matching globals with imports
+  --jsx-dev                 Use React's automatic runtime in development mode
   --jsx-factory=...         What to use for JSX instead of React.createElement
   --jsx-fragment=...        What to use for JSX instead of React.Fragment
-  --jsx=...                 Set to "preserve" to disable transforming JSX to JS
+  --jsx-import-source=...   Override the package name for the automatic runtime
+                            (default "react")
+  --jsx=...                 Set to "automatic" to use React's automatic runtime
+                            or to "preserve" to disable transforming JSX to JS
   --keep-names              Preserve "name" on functions and classes
   --legal-comments=...      Where to place legal comments (none | inline |
                             eof | linked | external, default eof when bundling

internal/bundler/bundler.go

@@ -1194,6 +1194,12 @@ func (s *scanner) maybeParseFile(
 	if len(resolveResult.JSXFragment) > 0 {
 		optionsClone.JSX.Fragment = config.DefineExpr{Parts: resolveResult.JSXFragment}
 	}
+	if resolveResult.JSX != config.TSJSXNone {
+		optionsClone.JSX.SetOptionsFromTSJSX(resolveResult.JSX)
+	}
+	if resolveResult.JSXImportSource != "" {
+		optionsClone.JSX.ImportSource = resolveResult.JSXImportSource
+	}
 	if resolveResult.UseDefineForClassFieldsTS != config.Unspecified {
 		optionsClone.UseDefineForClassFields = resolveResult.UseDefineForClassFieldsTS
 	}

internal/bundler/bundler_default_test.go

@@ -539,6 +539,88 @@ func TestJSXConstantFragments(t *testing.T) {
 	})
 }
 
+func TestJSXAutomaticImportsCommonJS(t *testing.T) {
+	default_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.jsx": `
+				import {jsx, Fragment} from './custom-react'
+				console.log(<div jsx={jsx}/>, <><Fragment/></>)
+			`,
+			"/custom-react.js": `
+				module.exports = {}
+			`,
+		},
+		entryPaths: []string{"/entry.jsx"},
+		options: config.Options{
+			Mode: config.ModeBundle,
+			JSX: config.JSXOptions{
+				AutomaticRuntime: true,
+			},
+			ExternalSettings: config.ExternalSettings{
+				PreResolve: config.ExternalMatchers{Exact: map[string]bool{
+					"react/jsx-runtime": true,
+				}},
+			},
+			AbsOutputFile: "/out.js",
+		},
+	})
+}
+
+func TestJSXAutomaticImportsES6(t *testing.T) {
+	default_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.jsx": `
+				import {jsx, Fragment} from './custom-react'
+				console.log(<div jsx={jsx}/>, <><Fragment/></>)
+			`,
+			"/custom-react.js": `
+				export function jsx() {}
+				export function Fragment() {}
+			`,
+		},
+		entryPaths: []string{"/entry.jsx"},
+		options: config.Options{
+			Mode: config.ModeBundle,
+			JSX: config.JSXOptions{
+				AutomaticRuntime: true,
+			},
+			ExternalSettings: config.ExternalSettings{
+				PreResolve: config.ExternalMatchers{Exact: map[string]bool{
+					"react/jsx-runtime": true,
+				}},
+			},
+			AbsOutputFile: "/out.js",
+		},
+	})
+}
+
+func TestJSXAutomaticSyntaxInJS(t *testing.T) {
+	default_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.js": `
+				console.log(<div/>)
+			`,
+		},
+		entryPaths: []string{"/entry.js"},
+		options: config.Options{
+			Mode: config.ModeBundle,
+			JSX: config.JSXOptions{
+				AutomaticRuntime: true,
+			},
+			ExternalSettings: config.ExternalSettings{
+				PreResolve: config.ExternalMatchers{Exact: map[string]bool{
+					"react/jsx-runtime": true,
+				}},
+			},
+			AbsOutputFile: "/out.js",
+		},
+		expectedScanLog: `entry.js: ERROR: The JSX syntax extension is not currently enabled
+NOTE: The esbuild loader for this file is currently set to "js" but it must be set to "jsx" to be able to parse JSX syntax. ` +
+			`You can use 'Loader: map[string]api.Loader{".js": api.LoaderJSX}' to do that.
+`,
+	})
+}
+
 func TestNodeModules(t *testing.T) {
 	default_suite.expectBundled(t, bundled{
 		files: map[string]string{

internal/bundler/bundler_tsconfig_test.go

@@ -601,6 +601,91 @@ func TestTsConfigNestedJSX(t *testing.T) {
 	})
 }
 
+func TestTsConfigReactJSX(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/entry.tsx": `
+				console.log(<><div/><div/></>)
+			`,
+			"/Users/user/project/tsconfig.json": `
+				{
+					"compilerOptions": {
+						"jsx": "react-jsx",
+						"jsxImportSource": "notreact"
+					}
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/entry.tsx"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+			ExternalSettings: config.ExternalSettings{
+				PreResolve: config.ExternalMatchers{Exact: map[string]bool{
+					"notreact/jsx-runtime": true,
+				}},
+			},
+		},
+	})
+}
+
+func TestTsConfigReactJSXDev(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/entry.tsx": `
+				console.log(<><div/><div/></>)
+			`,
+			"/Users/user/project/tsconfig.json": `
+				{
+					"compilerOptions": {
+						"jsx": "react-jsxdev"
+					}
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/entry.tsx"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+			ExternalSettings: config.ExternalSettings{
+				PreResolve: config.ExternalMatchers{Exact: map[string]bool{
+					"react/jsx-dev-runtime": true,
+				}},
+			},
+		},
+	})
+}
+
+func TestTsConfigReactJSXWithDevInMainConfig(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/entry.tsx": `
+				console.log(<><div/><div/></>)
+			`,
+			"/Users/user/project/tsconfig.json": `
+				{
+					"compilerOptions": {
+						"jsx": "react-jsx"
+					}
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/entry.tsx"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+			JSX: config.JSXOptions{
+				Development: true,
+			},
+			ExternalSettings: config.ExternalSettings{
+				PreResolve: config.ExternalMatchers{Exact: map[string]bool{
+					"react/jsx-dev-runtime": true,
+				}},
+			},
+		},
+	})
+}
+
 func TestTsconfigJsonBaseUrl(t *testing.T) {
 	tsconfig_suite.expectBundled(t, bundled{
 		files: map[string]string{

internal/bundler/snapshots/snapshots_default.txt

@@ -1415,6 +1415,42 @@ console.log(replace.test);
 console.log(collide);
 console.log(re_export);
 
+================================================================================
+TestJSXAutomaticImportsCommonJS
+---------- /out.js ----------
+// custom-react.js
+var require_custom_react = __commonJS({
+  "custom-react.js"(exports, module) {
+    module.exports = {};
+  }
+});
+
+// entry.jsx
+var import_custom_react = __toESM(require_custom_react());
+import { Fragment as Fragment2, jsx as jsx2 } from "react/jsx-runtime";
+console.log(/* @__PURE__ */ jsx2("div", {
+  jsx: import_custom_react.jsx
+}), /* @__PURE__ */ jsx2(Fragment2, {
+  children: /* @__PURE__ */ jsx2(import_custom_react.Fragment, {})
+}));
+
+================================================================================
+TestJSXAutomaticImportsES6
+---------- /out.js ----------
+// custom-react.js
+function jsx() {
+}
+function Fragment() {
+}
+
+// entry.jsx
+import { Fragment as Fragment2, jsx as jsx2 } from "react/jsx-runtime";
+console.log(/* @__PURE__ */ jsx2("div", {
+  jsx
+}), /* @__PURE__ */ jsx2(Fragment2, {
+  children: /* @__PURE__ */ jsx2(Fragment, {})
+}));
+
 ================================================================================
 TestJSXConstantFragments
 ---------- /out.js ----------

internal/bundler/snapshots/snapshots_tsconfig.txt

@@ -314,6 +314,66 @@ function fib(input) {
 // Users/user/project/entry.ts
 console.log(fib(10));
 
+================================================================================
+TestTsConfigReactJSX
+---------- /Users/user/project/out.js ----------
+// Users/user/project/entry.tsx
+import { Fragment, jsx, jsxs } from "notreact/jsx-runtime";
+console.log(/* @__PURE__ */ jsxs(Fragment, {
+  children: [
+    /* @__PURE__ */ jsx("div", {}),
+    /* @__PURE__ */ jsx("div", {})
+  ]
+}));
+
+================================================================================
+TestTsConfigReactJSXDev
+---------- /Users/user/project/out.js ----------
+// Users/user/project/entry.tsx
+import { Fragment, jsxDEV } from "react/jsx-dev-runtime";
+console.log(/* @__PURE__ */ jsxDEV(Fragment, {
+  children: [
+    /* @__PURE__ */ jsxDEV("div", {}, void 0, false, {
+      fileName: "Users/user/project/entry.tsx",
+      lineNumber: 2,
+      columnNumber: 19
+    }, this),
+    /* @__PURE__ */ jsxDEV("div", {}, void 0, false, {
+      fileName: "Users/user/project/entry.tsx",
+      lineNumber: 2,
+      columnNumber: 25
+    }, this)
+  ]
+}, void 0, true, {
+  fileName: "Users/user/project/entry.tsx",
+  lineNumber: 2,
+  columnNumber: 17
+}, this));
+
+================================================================================
+TestTsConfigReactJSXWithDevInMainConfig
+---------- /Users/user/project/out.js ----------
+// Users/user/project/entry.tsx
+import { Fragment, jsxDEV } from "react/jsx-dev-runtime";
+console.log(/* @__PURE__ */ jsxDEV(Fragment, {
+  children: [
+    /* @__PURE__ */ jsxDEV("div", {}, void 0, false, {
+      fileName: "Users/user/project/entry.tsx",
+      lineNumber: 2,
+      columnNumber: 19
+    }, this),
+    /* @__PURE__ */ jsxDEV("div", {}, void 0, false, {
+      fileName: "Users/user/project/entry.tsx",
+      lineNumber: 2,
+      columnNumber: 25
+    }, this)
+  ]
+}, void 0, true, {
+  fileName: "Users/user/project/entry.tsx",
+  lineNumber: 2,
+  columnNumber: 17
+}, this));
+
 ================================================================================
 TestTsConfigWithStatementAlwaysStrictFalse
 ---------- /Users/user/project/out.js ----------