TypeScript

Oxc transformer supports transforming TypeScript to JavaScript.

import { transform } from "oxc-transform";

const result = await transform("lib.ts", sourceCode, {
  typescript: {
    jsxPragma: "React.createElement",
    jsxPragmaFrag: "React.Fragment",
    onlyRemoveTypeImports: false,
    allowNamespaces: true,
    removeClassFieldsWithoutInitializer: false,
    rewriteImportExtensions: false,
    optimizeConstEnums: false,
    optimizeEnums: false,
  },
});
`````````js
import { transform } from "oxc-transform";

const result = await transform("lib.ts", sourceCode, {
  typescript: {
    removeClassFieldsWithoutInitializer: true,
  },
  assumptions: {
    setPublicClassFields: true,
  },
});
`````````ts [input.ts]
import { Something1 } from "./somewhere";

type Something2 = Exclude<string | number, string>;

export class Foo {
  @test
  foo(input1: Something1, input2: Something2) {}
}
`````````js [output(typescript_compiler).js]
// omit helper functions
var _a;
import { Something1 } from "./somewhere";
export class Foo {
  foo(input1, input2) {}
}
__decorate(
  [
    test,
    __metadata("design:type", Function),
    __metadata("design:paramtypes", [
      typeof (_a = typeof Something1 !== "undefined" && Something1) === "function" ? _a : Object,
      Number, // [!code highlight]
    ]),
    __metadata("design:returntype", void 0),
  ],
  Foo.prototype,
  "foo",
  null,
);
`````````js [output.js]
// omit helper functions
import { Something1 } from "./somewhere";
var _ref;
export class Foo {
  foo(input1, input2) {}
}
_decorate(
  [
    test,
    Reflect.metadata("design:paramtypes", [Something1, Number]),
    _decorateMetadata("design:type", Function),
    _decorateMetadata("design:paramtypes", [
      typeof (_ref = typeof Something1 !== "undefined" && Something1) === "function"
        ? _ref
        : Object,
      Object,
    ]),
    _decorateMetadata("design:returntype", void 0),
  ],
  Foo.prototype,
  "foo",
  null,
);
`````````js
import { transform } from "oxc-transform";

const result = await transform("lib.ts", sourceCode, {
  typescript: {
    optimizeConstEnums: true,
    optimizeEnums: true,
  },
});
`````````ts
namespace Foo {
  export let bar = 1; 
}
console.log(Foo.bar);
`````````ts [input.ts]
namespace Foo {
  export const bar = 1;
}
namespace Foo {
  export const baz = bar;
}
`````````js [output(typescript_compiler).js]
var Foo;
(function (Foo) {
  Foo.bar = 1;
})(Foo || (Foo = {}));
(function (Foo) {
  Foo.baz = Foo.bar; 
})(Foo || (Foo = {}));