Parcel automatically transpiles TypeScript whenever you use a
tsconfig.json file can be used to configure some aspects of the transpilation. Currently, JSX options are supported, as well as the
useDefineForClassFields options. See the TSConfig reference for details.
Because Parcel processes each file individually, it implicitly enables the
isolatedModules option. This means that some TypeScript features like
const enum that require cross-file type information to compile will not work. To be warned about usages of these features in your IDE and during type checking, you should enable this option in your
TSC is the official TypeScript compiler from Microsoft. While Parcel’s default transpiler for TypeScript is much faster than TSC, you may need to use TSC if you are using some configuration in
tsconfig.json that Parcel doesn't support. In these cases, you can use the
@parcel/transformer-typescript-tsc plugin by adding it to your
Even when using TSC, Parcel still processes each TypeScript file individually, so the note about about
isolatedModules still applies. In addition, some resolution features such as
paths are not currently supported by Parcel. The TSC transformer also does not perform any type checking (see below).
You can also choose to use Babel to compile TypeScript. If a Babel config containing
@babel/preset-typescript is found, Parcel will use it to compile
Parcel does not currently support the
paths options in
tsconfig.json, which are TypeScript specific resolution extensions. Instead, you may be able to use Parcel's tilde or absolute specifiers to accomplish a similar goal. See Configuring other tools in the dependency resolution docs for information about how to configure TypeScript to support these.
When building a library, Parcel can extract the types from your entry point and generate a
.d.ts file. Use the
types field in
package.json alongside a target such as
module to enable this.
See Building a library with Parcel for more details.
By default, Parcel does not perform any type checking. The recommended way to type check is by using an editor with TypeScript support (such as VSCode), and using
tsc to type check your code in CI. You can configure this using npm scripts to run alongside your build, tests, and linting.
Experimental validator plugin#
@parcel/validator-typescript plugin is an experimental way to type check within your Parcel build. It runs in the background after bundles are generated. Make sure the
include option in
tsconfig.json includes all of your source files.