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Version namespacing

DUIL v3.0.1 introduces version-namespaced components and CSS tokens. This allows different DUIL versions to coexist in microFE applications without components and styles from one version interfering with another.

The short version

If your application directly uses DUIL components, CSS tokens, or custom selectors targeting DUIL components, run the migration helper after upgrading.

npm i @dhl-official/react-library@3.0.1 --save-exact \
  && npm i @dhl-official/tokens@3.0.1 --save-exact \
  && npx duil-prefix-namespace --write

The @dhl-official/react-library and @dhl-official/tokens versions must match.

1. Do I need to migrate?​

The migration is required if your application contains any of these:

Component tags​

<duil301-dhl-button>
<duil301-dhl-input-field>

Or references such as:

document.querySelector("duil301-dhl-button");

CSS tokens​

border-radius: var(--duil301-dui-size-radius-md);
color: var(--duil301-dui-colors-foreground-primary);

Custom component styling​

duil301-dhl-button a {
  /* custom styling */
}

Tests​

Tests that reference DUIL component tags:

cy.get("duil301-dhl-button");
No direct DUIL references?

If your application does not directly reference DUIL component tags, tokens, or selectors, no source-code migration is required.

2. What changed?​

DUIL components and tokens now include the DUIL version in their namespace.

Before v3.0.1After v3.0.1
duil301-dhl-buttonduil301-dhl-button
HTMLDuil301DhlButtonElementHTMLDuil301DhlButtonElement
--duil301-dui-size-radius-md--duil301-dui-size-radius-md
Version → namespace

DUIL 3.0.1 → duil301-duil301-dhl-button
DUIL 3.0.2 → duil302-duil301-dhl-button

The 301 in duil301 represents DUIL 3.0.1.

When you upgrade DUIL, the namespace changes with the version.

This means different DUIL versions can be loaded by different microFEs without using the same component and token names.

3. Run the migration​

DUIL provides duil-prefix-namespace to automatically update your source code.

Preview the changes​

Before modifying anything, run:

npx duil-prefix-namespace --dry-run

This shows which files contain DUIL references that need to be updated.

Apply the changes​

Once you're happy with the result:

npx duil-prefix-namespace --write

The migration helper handles:

  • DUIL component tags
  • Stencil HTML element types
  • DUIL CSS tokens
  • Previously namespaced components and tokens
  • References used by tests

It preserves HTML/JSX attributes and expressions that should not be namespace-transformed.

Recommended workflow

Run --dry-run first, review the files, then run --write.

4. Upgrade DUIL​

From v3.0.1 onwards, the namespace migration is part of the standard DUIL upgrade process.

Use the following command when upgrading to a new version:

npm i @dhl-official/react-library@<version> --save-exact \
  && npm i @dhl-official/tokens@<version> --save-exact \
  && npx duil-prefix-namespace --write

For example:

npm i @dhl-official/react-library@3.0.1 --save-exact \
  && npm i @dhl-official/tokens@3.0.1 --save-exact \
  && npx duil-prefix-namespace --write
Keep package versions in sync

Always install the same version of:

  • @dhl-official/react-library
  • @dhl-official/tokens

If the versions don't match, DUIL styles may not render correctly.

Don't skip the migration

If the namespace migration is not run, your application may still reference the old component and token names.

This can cause the application build to fail.

5. MicroFE applications​

If your application is a microFE, there is one additional setup required:

Each microFE must initialize its own DUIL instance.

01 → Add the DUIL initialization​

Add the following to the root application file that is exposed to the shell:

import "@dhl-official/tokens/index.css";
import { initDUIL } from "@dhl-official/react-library";

initDUIL();

02 → Find the exposed entry point​

Check your webpack.config.js to see which application entry point is exposed:

exposes: {
  './App': './src/App',
}

The DUIL initialization should be located in the corresponding exposed application entry point.

For example:

webpack.config.js
      │
      └── './App'
            │
            ▼
        src/App.tsx
            │
            ├── import '@dhl-official/tokens/index.css'
            ├── import { initDUIL }
            └── initDUIL()

03 → Check before adding​

Before adding the initialization, check whether initDUIL() is already called in the exposed application entry point.

If it is already there, do not add it again.

Before and after DUIL namespaces: different microFEs previously shared global DUIL component and token names, while version-specific namespaces allow multiple DUIL versions to coexist safely.

Migration checklist​

Follow these steps when upgrading to a new DUIL version.

01 → Update DUIL packages​

Upgrade @dhl-official/react-library and @dhl-official/tokens to the same version.

02 → Preview the migration​

Run npx duil-prefix-namespace --dry-run and review the files that will be changed.

03 → Apply the migration​

Run npx duil-prefix-namespace --write.

04 → Check your microFE setup​

If you're using microFEs, verify that initDUIL() is called from the exposed application entry point.

05 → Build & test​

Build the application and run your tests to make sure everything works as expected.

Remember

Every DUIL upgrade from v3.0.1 onwards requires the namespace migration step.

npx duil-prefix-namespace --write