module: add module.stripTypeScriptTypes · nodejs/node@6575b76

Register a module that exports [hooks][] that customize Node.js module

resolution and loading behavior. See [Customization hooks][].

## `module.stripTypeScriptTypes(code[, options])`

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added: REPLACEME

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> Stability: 1.0 - Early development

* `code` {string} The code to strip type annotations from.

* `options` {Object}

* `mode` {string} **Default:** `'strip'`. Possible values are:

* `'strip'` Only strip type annotations without performing the transformation of TypeScript features.

* `'transform'` Strip type annotations and transform TypeScript features to JavaScript.

* `sourceMap` {boolean} **Default:** `false`. Only when `mode` is `'transform'`, if `true`, a source map

will be generated for the transformed code.

* `sourceUrl` {string} Specifies the source url used in the source map.

* Returns: {string} The code with type annotations stripped.

`module.stripTypeScriptTypes()` removes type annotations from TypeScript code. It

can be used to strip type annotations from TypeScript code before running it

with `vm.runInContext()` or `vm.compileFunction()`.

By default, it will throw an error if the code contains TypeScript features

that require transformation such as `Enums`,

see [type-stripping][] for more information.

When mode is `'transform'`, it also transforms TypeScript features to JavaScript,

see [transform TypeScript features][] for more information.

When mode is `'strip'`, source maps are not generated, because locations are preserved.

If `sourceMap` is provided, when mode is `'strip'`, an error will be thrown.

_WARNING_: The output of this function should not be considered stable across Node.js versions,

due to changes in the TypeScript parser.

```mjs

import { stripTypeScriptTypes } from 'node:module';

const code = 'const a: number = 1;';

const strippedCode = stripTypeScriptTypes(code);

console.log(strippedCode);

// Prints: const a = 1;

```

```cjs

const { stripTypeScriptTypes } = require('node:module');

const code = 'const a: number = 1;';

const strippedCode = stripTypeScriptTypes(code);

console.log(strippedCode);

// Prints: const a = 1;

```

If `sourceUrl` is provided, it will be used appended as a comment at the end of the output:

```mjs

import { stripTypeScriptTypes } from 'node:module';

const code = 'const a: number = 1;';

const strippedCode = stripTypeScriptTypes(code, { mode: 'strip', sourceUrl: 'source.ts' });

console.log(strippedCode);

// Prints: const a = 1\n\n//# sourceURL=source.ts;

```

```cjs

const { stripTypeScriptTypes } = require('node:module');

const code = 'const a: number = 1;';

const strippedCode = stripTypeScriptTypes(code, { mode: 'strip', sourceUrl: 'source.ts' });

console.log(strippedCode);

// Prints: const a = 1\n\n//# sourceURL=source.ts;

```

When `mode` is `'transform'`, the code is transformed to JavaScript:

```mjs

import { stripTypeScriptTypes } from 'node:module';

const code = `

namespace MathUtil {

export const add = (a: number, b: number) => a + b;

}`;

const strippedCode = stripTypeScriptTypes(code, { mode: 'transform', sourceMap: true });

console.log(strippedCode);

// Prints:

// var MathUtil;

// (function(MathUtil) {

// MathUtil.add = (a, b)=>a + b;

// })(MathUtil || (MathUtil = {}));

// # sourceMappingURL=data:application/json;base64, ...

```

```cjs

const { stripTypeScriptTypes } = require('node:module');

const code = `

namespace MathUtil {

export const add = (a: number, b: number) => a + b;

}`;

const strippedCode = stripTypeScriptTypes(code, { mode: 'transform', sourceMap: true });

console.log(strippedCode);

// Prints:

// var MathUtil;

// (function(MathUtil) {

// MathUtil.add = (a, b)=>a + b;

// })(MathUtil || (MathUtil = {}));

// # sourceMappingURL=data:application/json;base64, ...

```

### `module.syncBuiltinESMExports()`

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[realm]: https://tc39.es/ecma262/#realm

[source map include directives]: https://sourcemaps.info/spec.html#h.lmz475t4mvbx

[transferrable objects]: worker_threads.md#portpostmessagevalue-transferlist

[transform TypeScript features]: typescript.md#typescript-features

[type-stripping]: typescript.md#type-stripping