Add support for TS type-only imports and exports

src/transformers/CJSImportTransformer.ts

@@ -300,6 +300,17 @@ export default class CJSImportTransformer extends Transformer {
     } else if (this.tokens.matches2(tt._export, tt.star)) {
       this.processExportStar();
       return true;
+    } else if (
+      this.tokens.matches3(tt._export, tt.name, tt.braceL) &&
+      this.tokens.matchesContextualAtIndex(this.tokens.currentIndex() + 1, ContextualKeyword._type)
+    ) {
+      // TS `export type {` case: just remove the export entirely.
+      this.tokens.removeInitialToken();
+      while (!this.tokens.matches1(tt.braceR)) {
+        this.tokens.removeToken();
+      }
+      this.tokens.removeToken();
+      return true;
     } else {
       throw new Error("Unrecognized export syntax.");
     }

src/transformers/ESMImportTransformer.ts

@@ -55,6 +55,18 @@ export default class ESMImportTransformer extends Transformer {
     if (this.tokens.matches2(tt._export, tt.braceL)) {
       return this.processNamedExports();
     }
+    if (
+      this.tokens.matches3(tt._export, tt.name, tt.braceL) &&
+      this.tokens.matchesContextualAtIndex(this.tokens.currentIndex() + 1, ContextualKeyword._type)
+    ) {
+      // TS `export type {` case: just remove the export entirely.
+      this.tokens.removeInitialToken();
+      while (!this.tokens.matches1(tt.braceR)) {
+        this.tokens.removeToken();
+      }
+      this.tokens.removeToken();
+      return true;
+    }
     return false;
   }
 

test/typescript-test.ts

@@ -1962,15 +1962,92 @@ describe("typescript transform", () => {
     );
   });
 
-  it("parses and removes import type statements", () => {
+  it("parses and removes import type statements in CJS mode", () => {
     assertTypeScriptResult(
       `
       import type foo from 'foo';
-      console.log(foo);
+      import bar from 'bar';
+      console.log(foo, bar);
+    `,
+      `"use strict";${IMPORT_DEFAULT_PREFIX}
+
+      var _bar = require('bar'); var _bar2 = _interopRequireDefault(_bar);
+      console.log(foo, _bar2.default);
+    `,
+    );
+  });
+
+  it("parses and removes named import type statements in CJS mode", () => {
+    assertTypeScriptResult(
+      `
+      import type {foo} from 'foo';
+      import {bar} from 'bar';
+      console.log(foo, bar);
     `,
       `"use strict";
 
-      console.log(foo);
+      var _bar = require('bar');
+      console.log(foo, _bar.bar);
+    `,
+    );
+  });
+
+  it("parses and removes import type statements in ESM mode", () => {
+    assertTypeScriptESMResult(
+      `
+      import type foo from 'foo';
+      import bar from 'bar';
+      console.log(foo, bar);
+    `,
+      `
+
+      import bar from 'bar';
+      console.log(foo, bar);
+    `,
+    );
+  });
+
+  it("parses and removes named import type statements in ESM mode", () => {
+    assertTypeScriptESMResult(
+      `
+      import type {foo} from 'foo';
+      import {bar} from 'bar';
+      console.log(foo, bar);
+    `,
+      `
+
+      import {bar} from 'bar';
+      console.log(foo, bar);
+    `,
+    );
+  });
+
+  it("parses and removes export type statements in CJS mode", () => {
+    assertTypeScriptResult(
+      `
+      import T from './T';
+      let x: T;
+      export type {T};
+    `,
+      `"use strict";${ESMODULE_PREFIX}${IMPORT_DEFAULT_PREFIX}
+      var _T = require('./T'); var _T2 = _interopRequireDefault(_T);
+      let x;
+      ;
+    `,
+    );
+  });
+
+  it("parses and removes export type statements in ESM mode", () => {
+    assertTypeScriptESMResult(
+      `
+      import T from './T';
+      let x: T;
+      export type {T};
+    `,
+      `
+      import T from './T';
+      let x;
+      ;
     `,
     );
   });