Semantic Versioning Components

Semantic versioning components follows a standardized approach to numbering releases based on the type and impact of changes made. This convention helps development teams understand the risk and effort associated with updating to newer component versions. Applying semantic versioning correctly requires understanding what constitutes breaking changes in the context of UI components.

What Is Semantic Versioning for Components

Semantic versioning (semver) uses a three-part version number format: MAJOR.MINOR.PATCH. Each segment has a specific meaning that communicates change impact. Major versions signal incompatible changes requiring code updates. Minor versions add functionality without breaking existing usage. Patch versions contain backwards-compatible bug fixes.

For design system components, this versioning scheme applies to the public API surface. The public API includes prop names and types, CSS class names, emitted events, slot names, and any other interface consumers rely upon. Changes to internal implementation details that do not affect the public API typically warrant patch versions.

How Semantic Versioning Components Works

Determining the correct version increment requires analyzing changes against the previous release. Component maintainers must consider how changes affect existing consumer code and whether updates require any action from consuming teams.

A patch version increment applies when fixing bugs that do not alter expected component behavior or API. Examples include correcting visual rendering issues, fixing accessibility problems that do not change the interaction model, or improving performance without changing the component interface.

A minor version increment applies when adding new capabilities that do not break existing usage patterns. This includes adding new optional props, introducing new components, exposing additional CSS custom properties for theming, or extending existing functionality in backwards-compatible ways.

A major version increment applies when changes require consumers to modify their code. Removing or renaming props, changing prop types, altering default behavior, removing components, or restructuring the package exports all constitute breaking changes requiring major version bumps.

Key Considerations

• The public API definition must be clearly documented for consistent versioning decisions
• Visual changes may be breaking if consumers depend on specific styling
• Accessibility improvements sometimes require major versions if interaction patterns change
• TypeScript type changes follow the same rules as runtime API changes
• Peer dependency requirements changes may warrant major versions

Common Questions

Are visual changes considered breaking changes?

Visual changes occupy a gray area in semantic versioning. Strictly speaking, semver applies to the programmatic API rather than visual output. However, design system consumers often have expectations about component appearance, and significant visual changes can break their applications from a user experience perspective.

Some design system teams adopt a pragmatic approach where significant visual changes trigger minor versions with clear documentation, while drastic redesigns warrant major versions. The key is setting clear expectations with consumers about what constitutes a breaking visual change in the specific design system context.

How should TypeScript type changes be versioned?

TypeScript types form part of the public API when published in a design system package. Narrowing types (making them more restrictive) constitutes a breaking change because previously valid consumer code may no longer compile. Widening types (making them more permissive) is generally non-breaking.

Adding new optional properties to type definitions is backwards-compatible and warrants a minor version. Removing properties, changing property types to incompatible values, or making optional properties required all require major version increments. Teams should treat TypeScript types with the same rigor as runtime API changes.

Summary

Semantic versioning provides a clear communication framework for component releases when applied consistently. Understanding what constitutes the public API and how different changes impact consumers enables accurate version number assignment. Clear guidelines and documentation help both maintainers and consumers navigate the versioning landscape effectively.