[@rollup/plugin-replace] options values explicitly passed undefined value

[Moriarty47]

// rollup.config.js
plugins: [
   replace({
      values: undefined,
   }) 
]
// source.js
Object.values({});
({}).values();
// output.js
Object.undefined({});
({}).undefined();

When options.values explicitly passed undefined value, it will replace all values, is this intended ?

[RagedPanda]

Not really intended, but it's how the shorthand works. The plugin accepts replacements either under values or directly on the options object (replace({ __DEV__: "true" })). The code is basically:

function getReplacements(options) {
  if (options.values) return Object.assign({}, options.values);
  const values = Object.assign({}, options);
  delete values.delimiters;
  delete values.include;
  // ... deletes the other known options
  return values;
}

So when values is falsy (undefined, null), it falls back to treating the whole options object as the replacement map. values isn't one of the keys it deletes, so the key values itself ends up as a replacement with the value undefined, which gets stringified, and every values token turns into undefined. Reproduced on 6.0.3, with or without preventAssignment.

The easy fix is to never pass it through as undefined:

replace({
  preventAssignment: true,
  values: myValues ?? {},
})

With values: {} the output is untouched. Might be worth an issue so the plugin also deletes values in the fallback branch. It's a one-line fix.