Export the legacy ESM build as a package subpath

[gilpanal]

Problem

The npm package includes a legacy ESM build:

dist/latency-test.legacy.esm.js

However, it cannot be imported through a package subpath because package.json only exports ".".

For example:

import "@adasp/latency-test/legacy"

currently fails because ./legacy is not defined in exports.

Importing directly from node_modules is possible, but fragile:

import "../../../../node_modules/@adasp/latency-test/dist/latency-test.legacy.esm.js"

Proposed change

Add a legacy subpath to package.json:

{
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "import": "./dist/latency-test.esm.js",
      "default": "./dist/latency-test.esm.js"
    },
    "./legacy": {
      "types": "./dist/index.d.ts",
      "import": "./dist/latency-test.legacy.esm.js",
      "default": "./dist/latency-test.legacy.esm.js"
    }
  }
}

This would allow consumers to use:

import "@adasp/latency-test/legacy"

Environment

• @adasp/latency-test: 1.2.0
• Bundler: Parcel 2