If you do not use Rollup already, install the corresponding Nx plugin as follows:

nxadd@nx/rollup

Make sure the version of@nx/rollup matches your other@nx/* package versions.

You can then configure Rollup to compile your library by adding abuild target to yourproject.json orpackage.json file. Here's an example:

{
"name":"my-awesome-lib",
"nx": {
"targets": {
"build": {
"executor":"@nx/rollup:rollup",
"options": {
"main":"packages/my-awesome-lib/src/index.ts"
}
}
}
}
}

{
"name":"my-awesome-lib",
"targets": {
"build": {
"executor":"@nx/rollup:rollup",
"options": {
"main":"packages/my-awesome-lib/src/index.ts"
}
}
}
}

If you happen to use the@nx/js:tsc executor already, you can also use theRollup configuration generator from the Nx Rollup plugin to automatically configure your project's build target.

You'll need to specifyformat,additionalEntryPoints andgenerateExportsField in the executor options. Here's an example:

{
"name":"my-awesome-lib",
"targets": {
"build": {
"executor":"@nx/rollup:rollup",
"options": {
"main":"packages/my-awesome-lib/src/index.ts",
"format": ["esm","cjs"],
"additionalEntryPoints": ["packages/my-awesome-lib/src/foo.ts"],
"generateExportsField":true
}
}
}
}

After compiling our package usingnx build my-awesome-lib we'll get the following output in ourdist folder.

my-awesome-lib
└─ .
├─ README.md
├─ foo.cjs.d.ts
├─ foo.cjs.js
├─ foo.esm.js
├─ index.cjs.d.ts
├─ index.cjs.js
├─ index.esm.js
├─ package.json
└─ src
├─ foo.d.ts
├─ index.d.ts
└─ lib
└─ my-awesome-lib.d.ts

And ourpackage.json will look like this:

{
"name":"my-awesome-lib",
"version":"0.0.1",
...
"type":"commonjs",
"main":"./index.cjs.js",
"typings":"./src/index.d.ts",
"exports": {
"./package.json":"./package.json",
".": {
"import":"./index.esm.js",
"default":"./index.cjs.js"
},
"./foo": {
"import":"./foo.esm.js",
"default":"./foo.cjs.js"
}
},
"module":"./index.esm.js"
}

Now consumers of your package can access the appropriate format for their codebase and you don't have to worry about maintaining the infrastructure to compile to both formats.