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kirillzyusko merged 3 commits into from
Apr 28, 2026
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docs: ButtonBase migration (extension) #1093

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docs: `ButtonBase` migration (extension)
kirillzyusko Apr 23, 2026
72eafec
fix: resolve non-blocking comment
kirillzyusko Apr 23, 2026
8c9dd83
Merge branch 'main' into feat/button-base-extension-docs
kirillzyusko Apr 28, 2026
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151 changes: 151 additions & 0 deletions packages/design-system-react/MIGRATION.md
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Expand Up @@ -7,6 +7,7 @@ This guide provides detailed instructions for migrating your project from one ve
- [General Extension Migration Guidance](#general-extension-migration-guidance)
- [From Extension Component Library](#from-extension-component-library)
- [Button Component](#button-component)
- [ButtonBase Component](#buttonbase-component)
- [ButtonIcon Component](#buttonicon-component)
- [Box Component](#box-component)
- [BannerAlert Component](#banneralert-component)
Expand Down Expand Up @@ -141,6 +142,156 @@ The design system Button adds these props:
- `loadingText` — custom text during loading state
- `className` — Tailwind utility class overrides (merged via `twMerge`)

### ButtonBase Component

`ButtonBase` is a low-level building block for styled buttons. It has significant API changes from the extension `component-library` version — most notably, polymorphism via `as`/`href` is replaced by the `asChild` composition pattern, and `Box`/`TextStyleUtilityProps` are no longer accepted.

#### Breaking Changes

##### Import Path

| Extension Pattern | Design System Migration |
| ---------------------------------------------------------------- | ---------------------------------------------------------------------- |
| `import { ButtonBase } from '../../component-library'` | `import { ButtonBase } from '@metamask/design-system-react'` |
| `import { ButtonBaseSize } from '../../component-library'` | `import { ButtonBaseSize } from '@metamask/design-system-react'` |
| `import type { ButtonBaseProps } from '../../component-library'` | `import type { ButtonBaseProps } from '@metamask/design-system-react'` |

##### Size Enum

`ButtonBaseSize` keeps the same values, but the default changes from `Md` to `Lg`.

| Extension Value | Design System Value | Notes |
| ---------------------------- | ---------------------------- | -------------------------------- |
| `ButtonBaseSize.Sm` (`'sm'`) | `ButtonBaseSize.Sm` (`'sm'`) | unchanged |
| `ButtonBaseSize.Md` (`'md'`) | `ButtonBaseSize.Md` (`'md'`) | unchanged; no longer the default |
| `ButtonBaseSize.Lg` (`'lg'`) | `ButtonBaseSize.Lg` (`'lg'`) | unchanged; **new default** |

##### State Props Renamed

| Extension Prop | Design System Prop | Notes |
| ------------------ | ------------------ | ------- |
| `disabled` | `isDisabled` | renamed |
| `loading` | `isLoading` | renamed |
| `block` | `isFullWidth` | renamed |
| `iconLoadingProps` | `loadingIconProps` | renamed |

##### Content Model

`ButtonBase` already uses `children` in the extension — no change. String children are wrapped in a `Text` component automatically; non-string children are rendered as-is.

##### Polymorphism Removed: `as` / `href` → `asChild`

The extension `ButtonBase` is polymorphic — `as` switches the root element between `button` and `a`, and an `href` prop auto-switches to `a`. The design system `ButtonBase` always renders a `<button>`. To render as an anchor, use the `asChild` composition prop and provide your own `<a>`.

| Extension Prop | Design System Migration |
| ------------------------ | ------------------------------------------------------------------------------- |
| `as="a"` / `as="button"` | Removed — always renders a `<button>`. Use `asChild` with your own `<a>`. |
| `href="..."` | Removed — wrap in `asChild` with `<a href="...">`. |
| `externalLink` | Removed — on your `<a>`, set `target="_blank"` and `rel="noopener noreferrer"`. |
| `target` / `rel` | Removed — set directly on your `<a>` inside `asChild`. |

##### Removed Props

| Extension Prop | Design System Migration |
| --------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `ellipsis` | Removed — for string children, pass `textProps={{ ellipsis: true }}` (forwarded to the inner `Text` wrapper, closest to legacy behavior). For non-string children, wrap them in a custom truncating element or add `className="truncate"` on the button. |
| `iconColor` | Removed — only affected the loading spinner in the legacy component. Pass `loadingIconProps={{ color: ... }}` instead. (Start/end icon colors already came from `startIconProps.color` / `endIconProps.color` — unchanged.) |
| `textDirection` | Removed — set the standard HTML `dir` attribute on the element. |
| Box/Text style utility props (`padding*`, `margin*`, `backgroundColor`, `color`, `borderRadius`, …) | Removed — use Tailwind `className` instead. |

#### New Props

The design system `ButtonBase` adds props not available in the extension version:

- `asChild` — render the button styling onto a child element (Radix-style composition, replaces `as`/`href`)
- `loadingText` — text displayed alongside the spinner while loading
- `loadingTextProps` — customize the loading `Text` component
- `startAccessory` / `endAccessory` — arbitrary `ReactNode` slots at start/end, alongside `startIconName` / `endIconName`

#### Migration Examples

##### Before (Extension)

```tsx
import { ButtonBase, ButtonBaseSize } from '../../component-library';
import { IconName } from '../../component-library';

<ButtonBase
size={ButtonBaseSize.Lg}
block
startIconName={IconName.Add}
disabled={!isValid}
loading={isSubmitting}
onClick={handleSubmit}
>
Submit
</ButtonBase>;
```

##### After (Design System)

```tsx
import {
ButtonBase,
ButtonBaseSize,
IconName,
} from '@metamask/design-system-react';

<ButtonBase
size={ButtonBaseSize.Lg}
isFullWidth
startIconName={IconName.Add}
isDisabled={!isValid}
isLoading={isSubmitting}
onClick={handleSubmit}
>
Submit
</ButtonBase>;
```

##### Rendering as an anchor (`as="a"` / `href` → `asChild`)

Before (Extension):

```tsx
import { ButtonBase } from '../../component-library';

<ButtonBase as="a" href="https://metamask.io" externalLink>
Open MetaMask
</ButtonBase>;
```

After (Design System):

```tsx
import { ButtonBase } from '@metamask/design-system-react';

<ButtonBase asChild>
<a href="https://metamask.io" target="_blank" rel="noopener noreferrer">
Open MetaMask
</a>
</ButtonBase>;
```

##### Loading with custom text (new)

The extension only renders a spinner during `loading`. The design system supports an optional loading label:

```tsx
import { ButtonBase } from '@metamask/design-system-react';

<ButtonBase isLoading loadingText="Submitting…">
Submit
</ButtonBase>;
```

#### API Differences

- Default `size` changed from `ButtonBaseSize.Md` to `ButtonBaseSize.Lg`
- Root element is always `<button>` unless `asChild` is used
- Box/Text style-utility props are no longer accepted — use `className` (Tailwind) for styling overrides
- Loading state supports an optional `loadingText` and `loadingTextProps`

### ButtonIcon Component

`ButtonIcon` is a compact, icon-only button. The design system version has significant API differences from the extension `component-library` version — pixel sizes shift, the icon color API moves under `iconProps`, polymorphism via `as`/`href` is removed, and a new `variant` prop is introduced.
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4 changes: 4 additions & 0 deletions packages/design-system-react/src/components/ButtonBase/README.mdx
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Expand Up @@ -452,6 +452,10 @@ The `style` prop should primarily be used for dynamic inline styles that cannot

<Controls of={ButtonBaseStories.Default} />

## Migration Guide

Migrating from `ui/components/component-library/button-base` in MetaMask Extension? See the [ButtonBase Migration Guide](../../../MIGRATION.md#buttonbase-component) for prop mappings, before/after examples, and breaking changes.

## References

[MetaMask Design System Guides](https://www.notion.so/MetaMask-Design-System-Guides-Design-f86ecc914d6b4eb6873a122b83c12940)
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