context.md

title
context Directive

:context assigns an object into a component instance context, reactively. r-context is an alias with the same behavior.

Use it when you want to pass multiple values to a component in one place, including fields that are not declared in props.

What it does

<MyComponent :context="{ title: pageTitle, theme: activeTheme }"></MyComponent>
<MyComponent r-context="{ title: pageTitle, theme: activeTheme }"></MyComponent>

In the component, title and theme become available as component context fields (or update existing ref fields when applicable).
When pageTitle or activeTheme changes, the component values are updated.

When to use :context

Use :context for object-style component input. r-context is equivalent and can be used interchangeably.

Use :prop-name="value" or r-bind:prop-name="value" (same single-prop binding behavior) when the prop is declared in the component props list.

Use object-form attribute binding (r-bind="{...}" or :="{...}") for normal host attribute fallthrough, not for component context assignment.

Example

<UserCard
  :user-id="selectedUserId"
  :context="{ badge: userBadge, canEdit: isAdmin }"
></UserCard>

const UserCard = defineComponent('<section>...</section>', {
  props: ['userId'],
  context: (head) => ({
    userId: head.props.userId,
    badge: head.props.badge,
    canEdit: head.props.canEdit,
  }),
})

In this example:

• userId comes from declared prop binding (:user-id)
• badge and canEdit come from :context

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