Extras

The extras config contains options to enable new/experimental features in Stencil, add & remove runtime for DOM features that require manipulations to polyfills, etc. For example, not all DOM APIs are fully polyfilled when using the Slot polyfill. Most of these are opt-in, since not all users require the additional runtime.

appendChildSlotFix

By default, the slot polyfill does not update appendChild() so that it appends new child nodes into the correct child slot like how shadow dom works. This is an opt-in polyfill for those who need it.

cloneNodeFix

By default, the runtime does not polyfill cloneNode() when cloning a component that uses the slot polyfill. This is an opt-in polyfill for those who need it.

enableImportInjection

In some cases, it can be difficult to lazily load Stencil components in a separate project that uses a bundler such as Vite.

Enabling this flag will allow downstream projects that consume a Stencil library and use a bundler such as Vite to lazily load the Stencil library's components.

In order for this flag to work:

1. The Stencil library must expose lazy loadable components, such as those created with the dist output target
2. The Stencil library must be recompiled with this flag set to true

This flag works by creating dynamic import statements for every lazily loadable component in a Stencil project. Users of this flag should note that they may see an increase in their bundle size.

Defaults to false.

experimentalImportInjection

caution

This flag has been deprecated in favor of enableImportInjection, which provides the same functionality. experimentalImportInjection will be removed in a future major version of Stencil.

In some cases, it can be difficult to lazily load Stencil components in a separate project that uses a bundler such as Vite.

This is an experimental flag that, when set to true, will allow downstream projects that consume a Stencil library and use a bundler such as Vite to lazily load the Stencil library's components.

In order for this flag to work:

1. The Stencil library must expose lazy loadable components, such as those created with the dist output target
2. The Stencil library must be recompiled with this flag set to true

This flag works by creating dynamic import statements for every lazily loadable component in a Stencil project. Users of this flag should note that they may see an increase in their bundle size.

Defaults to false.

experimentalScopedSlotChanges

This option updates runtime behavior for Stencil's support of slots in scoped components to match more closely with the native Shadow DOM behaviors.

When set to true, the following behaviors will be applied:

• Stencil will hide projected nodes that do not have a destination slot (#2778) (since v4.10.0)
• The textContent getter will return the text content of all nodes located in a slot (since v4.10.0)
• The textContent setter will overwrite all nodes located in a slot (since v4.10.0)

Defaults to false.

note

These behaviors only apply to components using scoped encapsulation!

experimentalSlotFixes

This option enables all current and future slot-related fixes. When enabled it will enable the following options, overriding their values if they are specified separately:

• slotChildNodesFix
• scopedSlotTextContentFix.
• appendChildSlotFix
• cloneNodeFix

Slot-related fixes to the runtime will be added over the course of Stencil v4, with the intent of making these the default behavior in Stencil v5. When set to true fixes for the following issues will be applied:

• Elements rendered outside of slot when shadow not enabled (#2641) (since v4.2.0)
• A slot gets the attribute hidden when it shouldn't (#4523) (since v4.7.0)
• Nested slots mis-ordered when not using Shadow DOM (#2997) (since v4.7.0)
• Inconsistent behavior: slot-fb breaks styling of default slot content in component with 'shadow: false' (#2937) (since v4.7.2)
• Slot content went missing within dynamic component (#4284) (since v4.8.2)
• Slot element loses its parent reference and disappears when its parent is rendered conditionally (#3913) (since v4.8.2)
• Failed to execute 'removeChild' on 'Node' (#3278) (since v4.9.0)
• React fails to manage children in Stencil slot (#2259) (since v4.9.0)
• Slot name is not updated when it is bind to a prop (#2982) (since 4.12.1)
• Conditionally rendered slots not working (#5335) (since 4.13.0)

note

New fixes enabled by this experimental flag are not subject to Stencil's semantic versioning policy.

lifecycleDOMEvents

Dispatches component lifecycle events. By default these events are not dispatched, but by enabling this to true these events can be listened for on window. Mainly used for testing.

Event Name	Description
stencil_componentWillLoad	Dispatched for each component's componentWillLoad.
stencil_componentWillUpdate	Dispatched for each component's componentWillUpdate.
stencil_componentWillRender	Dispatched for each component's componentWillRender.
stencil_componentDidLoad	Dispatched for each component's componentDidLoad.
stencil_componentDidUpdate	Dispatched for each component's componentDidUpdate.
stencil_componentDidRender	Dispatched for each component's componentDidRender.

scopedSlotTextContentFix

An experimental flag that when set to true, aligns the behavior of invoking the textContent getter/setter on a scoped component to act more like a component that uses the shadow DOM. Specifically, invoking textContent on a component will adhere to the return values described in MDN's article on textContent. Defaults to false.

scriptDataOpts

It is possible to assign data to the actual <script> element's data-opts property, which then gets passed to Stencil's initial bootstrap. This feature is only required for very special cases and rarely needed. When set to false it will not read this data. Defaults to false.

slotChildNodesFix

For browsers that do not support shadow dom (IE11 and Edge 18 and below), slot is polyfilled to simulate the same behavior. However, the host element's childNodes and children getters are not patched to only show the child nodes and elements of the default slot. Defaults to false.