Kosko supports ECMAScript modules (ESM). You can write components and environments in native ESM files.
Node.js v12 or above is required for ESM. However, Node.js v14.8.0 or above is recommended because top-level await is supported without flags in this version.
You don't have to modify any config in
kosko.toml at all. To start using ESM, you can either set
package.json as below.
Or rename file extension as
.mjs. See Node.js documentation for more information.
@kosko/env is imported in ESM, it returns a
Promise instead. This is because
import() is asynchronous. You MUST add
await when retrieving environment variables as below.
You can use
@kosko/generate package directly. The following is a basic example.
There's no much difference between CommonJS and ESM when using Kosko programmatically. However, it could be troublesome if you are going to use both CommonJS and ESM at the same time. In Node.js, ESM has its own separate cache, which means there are two isolated instances of
Environment in CommonJS and ESM and both must be initialized separately.
It's recommended to use only one module type. If you really need to use both, here's an example of how to initialize them.