Using Parcel 2 programatically

[m-allanson]

I am trying to use @parcel/core to programatically create some bundles in an existing project. See here for an example config: https://github.com/m-allanson/parcelish/blob/master/scripts/bundle.js

However I'm running into an issue where the project's package.json file seems to be overriding some of the options passed into Parcel.

Here's roughly how I'm running Parcel:

// bundle.js
let bundler = new Parcel({
  defaultConfig: {
    ...defaultConfigContents,
    filePath: require.resolve("@parcel/config-default"),
  },
  entries: "src/target.js",
  isLibrary: true,
  mode: "production",
  outputFormat: "esmodule",
  target: {
    outputFormat: "esmodule",
    distDir: "dist",
  },
});

await bundler.run();

Note that the package.json contains a main entry, but I don't want Parcel to use it.

{
  "name": "example-project",
  "main": "src/index.js",
// ...

When I run the bundling, Parcel writes each bundle to src/index.js, instead of writing to the dist directory.

If I remove "main": "src/index.js", from the package.json, Parcel will output to the dist directory instead. I'd like this behaviour without having to remove the main property from the package.json file.

My questions:

• Is this expected behaviour, or am I doing something odd?
• Can I tell Parcel to ignore the package.json file, and only use the options that are provided by bundle.js?
• Can I manually specify a destination for a target? The API docs mention a distEntry value for Target. However, that value is not present on PackageTargetDescriptor, so I can't see a way of manually specifying it.

Here's a runnable example: https://github.com/m-allanson/parcelish

[mischnic]

Can I tell Parcel to ignore the package.json file, and only use the options that are provided by bundle.js?

I've looked at the code and passing a targets property in the options should cause package.json to be ignored. Not sure why this happens

However, that value is not present on PackageTargetDescriptor,

https://v2.parceljs.org/plugin-system/api/#PackageTargetDescriptor is used in a package.json, where package.json#default would be used as the distEntry for package.json#targets.default

So I guess it should be an optional property here: https://v2.parceljs.org/plugin-system/api/#TargetDescriptor

[m-allanson]

Thanks! I’ll investigate some more later next week.

[navaru]

Change

for (const module in config) {
  let task = async () => {
    let bundler = new Parcel({
      entries: config[module].entry,
      target: config[module].target, // <-- here is the problem

to

for (const module in config) {
  let task = async () => {
    let bundler = new Parcel({
      entries: config[module].entry,
      targets: { [module]: config[module].target },  // <-- this is the fix

[m-allanson]

😱 thank you @navaru! That did the trick.

[m-allanson]

Thanks both for your replies. For anyone looking to use Parcel 2 like this, here's the working code that I ended up with:

https://github.com/stylelint/stylelint/blob/642bd3201277a42e9cf8cd705a663795d92b32bd/scripts/bundle-esm.js

Note that Parcel has a private API _getResolvedParcelOptions that you can use to verify that your options are resolved as you expected. It can be useful to help you understand why Parcel is not doing what you want it to :)

In my case I was not specifying the targets correctly, so I think Parcel was falling back to checking the package.json file for that info.

[ivoba]

I have a similar problem, with also a main entry in package.json that should be ignored.

My setup:

 "@parcel/config-default": "^2.0.0-nightly.778",
 "@parcel/core": "^2.0.0-nightly.776",

calling Parcel via API:

const parcel = new Parcel({
    entries: path.join(__dirname, "../views/index.html"),
    defaultConfig: require.resolve("@parcel/config-default"),
    logLevel: 'verbose',
    targets: {
      default: {
        distDir: path.join(__dirname, "../dist"),
        distEntry: 'index.html',
        source: path.join(__dirname, "../views/index.html")
      },
    },
    mode: "production",
  })

await parcel.run().catch(err => console.log(err))

But there is no output at all, neither in console nor are files generated.

Also it seems redundant to declare entries and again in targets.
I am also not sure which target is called eventually?

node -v
v14.16.1

Any Ideas?

[padcom]

@ivoba Are you by any chance trying to get it to work with Electron app? That Node.js version 14.16 looks familiar :)