API Reference
Use this page to choose the right FAST Element import path and then browse the generated API reference for the public surface of each entrypoint.
Root vs. path exports
The root package export, @microsoft/fast-element, is the primary entrypoint for
FAST Element's component authoring APIs. It is the best default when you are
building custom elements with FASTElement, html, css, attr, directives,
observables, state helpers, and other core primitives.
FAST Element 3.x also publishes focused path exports. Use a path export when you want a smaller, feature-specific entrypoint or when the API is path-only. The path-only entrypoints should always be imported from their documented package paths rather than from the package root.
Common import choices
| Need | Import from | Reference |
|---|---|---|
| Core component authoring APIs | @microsoft/fast-element |
Root API reference |
| Declarative HTML templates | @microsoft/fast-element/declarative.js |
Declarative API reference and Declarative HTML overview |
| Server-rendered hydration | @microsoft/fast-element/hydration.js |
Hydration flow and path export list |
| W3C Context protocol helpers | @microsoft/fast-element/context.js |
Context API reference |
| Dependency injection container APIs | @microsoft/fast-element/di.js |
DI API reference and Dependency Injection guide |
Individual core features, such as html, css, attr, or directives |
The matching path export, such as @microsoft/fast-element/html.js |
Path exports |
Stability tags
The generated API pages include release-tag callouts from API Extractor:
- Public APIs are the supported surface for production code.
- Beta APIs are preview APIs that can change based on feedback.
- Alpha APIs are early previews and should be treated as less stable than beta APIs.
- Internal APIs are not intended for application code, even when they appear in a type signature or generated page.
Prefer public APIs when possible. If a generated page includes a beta or alpha notice, review the callout before depending on that symbol in production code.
Generated API docs
The API reference pages are generated from FAST Element's API Extractor output
and should not be edited by hand. Start with the generated
@microsoft/fast-element root reference for the
main package surface, then use the path-export references for focused APIs:
@microsoft/fast-element/declarative.js@microsoft/fast-element/context.js@microsoft/fast-element/di.js
For the complete list of supported package paths, see the Path Exports page.