Refactor output to immediately export default

Author: wooorm

packages/mdx/lib/plugin/recma-document.js

@@ -241,7 +241,9 @@ export function recmaDocument(options) {
           child.expression.type === 'JSXFragment')
       ) {
         content = true
-        replacement.push(...createMdxContent(child.expression, Boolean(layout)))
+        replacement.push(
+          ...createMdxContent(child.expression, outputFormat, Boolean(layout))
+        )
       } else {
         // This catch-all branch is because plugins might add other things.
         // Normally, we only have import/export/jsx, but just add whatever’s
@@ -252,7 +254,9 @@ export function recmaDocument(options) {
 
     // If there was no JSX content at all, add an empty function.
     if (!content) {
-      replacement.push(...createMdxContent(undefined, Boolean(layout)))
+      replacement.push(
+        ...createMdxContent(undefined, outputFormat, Boolean(layout))
+      )
     }
 
     exportedIdentifiers.push(['MDXContent', 'default'])
@@ -305,11 +309,6 @@ export function recmaDocument(options) {
           ]
         }
       })
-    } else {
-      replacement.push({
-        type: 'ExportDefaultDeclaration',
-        declaration: {type: 'Identifier', name: 'MDXContent'}
-      })
     }
 
     tree.body = replacement
@@ -497,14 +496,16 @@ export function recmaDocument(options) {
   }
 
   /**
-   * @param {Readonly<Expression> | undefined} [content]
+   * @param {Readonly<Expression> | undefined} content
    *   Content.
+   * @param {'function-body' | 'program'} outputFormat
+   *   Output format.
    * @param {boolean | undefined} [hasInternalLayout=false]
    *   Whether there’s an internal layout (default: `false`).
-   * @returns {Array<FunctionDeclaration>}
+   * @returns {Array<ExportDefaultDeclaration | FunctionDeclaration>}
    *   Functions.
    */
-  function createMdxContent(content, hasInternalLayout) {
+  function createMdxContent(content, outputFormat, hasInternalLayout) {
     /** @type {JSXElement} */
     const element = {
       type: 'JSXElement',
@@ -597,6 +598,23 @@ export function recmaDocument(options) {
       }
     })
 
+    /** @type {FunctionDeclaration} */
+    const declaration = {
+      type: 'FunctionDeclaration',
+      id: {type: 'Identifier', name: 'MDXContent'},
+      params: [
+        {
+          type: 'AssignmentPattern',
+          left: {type: 'Identifier', name: 'props'},
+          right: {type: 'ObjectExpression', properties: []}
+        }
+      ],
+      body: {
+        type: 'BlockStatement',
+        body: [{type: 'ReturnStatement', argument: result}]
+      }
+    }
+
     return [
       {
         type: 'FunctionDeclaration',
@@ -615,21 +633,9 @@ export function recmaDocument(options) {
           ]
         }
       },
-      {
-        type: 'FunctionDeclaration',
-        id: {type: 'Identifier', name: 'MDXContent'},
-        params: [
-          {
-            type: 'AssignmentPattern',
-            left: {type: 'Identifier', name: 'props'},
-            right: {type: 'ObjectExpression', properties: []}
-          }
-        ],
-        body: {
-          type: 'BlockStatement',
-          body: [{type: 'ReturnStatement', argument: result}]
-        }
-      }
+      outputFormat === 'program'
+        ? {type: 'ExportDefaultDeclaration', declaration}
+        : declaration
     ]
   }
 }

packages/mdx/readme.md

@@ -520,8 +520,7 @@ Configuration for `createProcessor` (TypeScript type).
     import {Fragment as _Fragment, jsx as _jsx} from 'react/jsx-runtime'
     export {number} from 'https://a.full/data.js'
     function _createMdxContent(props) { /* … */ }
-    function MDXContent(props = {}) { /* … */ }
-    export default MDXContent
+    export default function MDXContent(props = {}) { /* … */ }
     ```
 
     </details>

packages/mdx/test/compile.js

@@ -1058,11 +1058,10 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
         '  };',
         '  return <_components.p><_components.em>{"a"}</_components.em></_components.p>;',
         '}',
-        'function MDXContent(props = {}) {',
+        'export default function MDXContent(props = {}) {',
         '  const {wrapper: MDXLayout} = props.components || ({});',
         '  return MDXLayout ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props);',
         '}',
-        'export default MDXContent;',
         ''
       ].join('\n')
     )
@@ -1076,11 +1075,10 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
         'function _createMdxContent(props) {',
         '  return <a {...b} c d="1" e={1} />;',
         '}',
-        'function MDXContent(props = {}) {',
+        'export default function MDXContent(props = {}) {',
         '  const {wrapper: MDXLayout} = props.components || ({});',
         '  return MDXLayout ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props);',
         '}',
-        'export default MDXContent;',
         ''
       ].join('\n')
     )
@@ -1099,11 +1097,10 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
           '  if (!c.d) _missingMdxReference("c.d", true);',
           '  return <><><a:b /><c.d /></></>;',
           '}',
-          'function MDXContent(props = {}) {',
+          'export default function MDXContent(props = {}) {',
           '  const {wrapper: MDXLayout} = props.components || ({});',
           '  return MDXLayout ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props);',
           '}',
-          'export default MDXContent;',
           'function _missingMdxReference(id, component) {',
           '  throw new Error("Expected " + (component ? "component" : "object") + " `" + id + "` to be defined: you likely forgot to import, pass, or provide it.");',
           '}',
@@ -1122,11 +1119,10 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
         'function _createMdxContent(props) {',
         '  return <><>{"a "}{}{" b"}</></>;',
         '}',
-        'function MDXContent(props = {}) {',
+        'export default function MDXContent(props = {}) {',
         '  const {wrapper: MDXLayout} = props.components || ({});',
         '  return MDXLayout ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props);',
         '}',
-        'export default MDXContent;',
         ''
       ].join('\n')
     )
@@ -1146,11 +1142,10 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
           '  }, _component0 = _components["a-b"];',
           '  return <>{<_component0></_component0>}</>;',
           '}',
-          'function MDXContent(props = {}) {',
+          'export default function MDXContent(props = {}) {',
           '  const {wrapper: MDXLayout} = props.components || ({});',
           '  return MDXLayout ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props);',
           '}',
-          'export default MDXContent;',
           ''
         ].join('\n')
       )
@@ -1169,11 +1164,10 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
         '  };',
         '  return <_components.p>{"Hello "}{props.name}</_components.p>;',
         '}',
-        'function MDXContent(props = {}) {',
+        'export default function MDXContent(props = {}) {',
         '  const {wrapper: MDXLayout} = props.components || ({});',
         '  return MDXLayout ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props);',
         '}',
-        'export default MDXContent;',
         ''
       ].join('\n')
     )
@@ -1201,10 +1195,9 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
           '  };',
           '  return <_components.p>{"a"}</_components.p>;',
           '}',
-          'function MDXContent(props = {}) {',
+          'export default function MDXContent(props = {}) {',
           '  return <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout>;',
           '}',
-          'export default MDXContent;',
           ''
         ].join('\n')
       )
@@ -1232,15 +1225,13 @@ test('@mdx-js/mdx: compile (JSX)', async function (t) {
           '  };',
           '  return <_components.p>{"a"}</_components.p>;',
           '}',
-          'function MDXContent(props = {}) {',
+          'export default function MDXContent(props = {}) {',
           '  const {wrapper: MDXLayout} = {',
           '    ..._provideComponents(),',
           '    ...props.components',
           '  };',
           '  return MDXLayout ? <MDXLayout {...props}><_createMdxContent {...props} /></MDXLayout> : _createMdxContent(props);',
-
           '}',
-          'export default MDXContent;',
           ''
         ].join('\n')
       )

packages/mdx/test/syntax.js

@@ -656,7 +656,7 @@ test('@mdx-js/mdx: syntax: MDX (JSX)', async function (t) {
         '    })',
         '  });',
         '}',
-        'function MDXContent(props = {}) {',
+        'export default function MDXContent(props = {}) {',
         '  const {wrapper: MDXLayout} = props.components || ({});',
         '  return MDXLayout ? _jsx(MDXLayout, {',
         '    ...props,',
@@ -665,7 +665,6 @@ test('@mdx-js/mdx: syntax: MDX (JSX)', async function (t) {
         '    })',
         '  }) : _createMdxContent(props);',
         '}',
-        'export default MDXContent;',
         ''
       ].join('\n')
     )
@@ -880,7 +879,7 @@ test('@mdx-js/mdx: syntax: MDX (ESM)', async function (t) {
         '    columnNumber: 1',
         '  }, this);',
         '}',
-        'function MDXContent(props = {}) {',
+        'export default function MDXContent(props = {}) {',
         '  const {wrapper: MDXLayout} = props.components || ({});',
         '  return MDXLayout ? _jsxDEV(MDXLayout, {',
         '    ...props,',
@@ -893,7 +892,6 @@ test('@mdx-js/mdx: syntax: MDX (ESM)', async function (t) {
         '    fileName: "path/to/file.js"',
         '  }, this) : _createMdxContent(props);',
         '}',
-        'export default MDXContent;',
         'function _missingMdxReference(id, component, place) {',
         '  throw new Error("Expected " + (component ? "component" : "object") + " `" + id + "` to be defined: you likely forgot to import, pass, or provide it." + (place ? "\\nIt’s referenced in your code at `" + place + "` in `path/to/file.js`" : ""));',
         '}',