public.d.ts•2.71 kB
/**
* Actions can return an object containing the two properties defined in this interface. Both are optional.
* - update: An action can have a parameter. This method will be called whenever that parameter changes,
* immediately after Svelte has applied updates to the markup. `ActionReturn` and `ActionReturn<undefined>` both
* mean that the action accepts no parameters.
* - destroy: Method that is called after the element is unmounted
*
* Additionally, you can specify which additional attributes and events the action enables on the applied element.
* This applies to TypeScript typings only and has no effect at runtime.
*
* Example usage:
* ```ts
* interface Attributes {
* newprop?: string;
* 'on:event': (e: CustomEvent<boolean>) => void;
* }
*
* export function myAction(node: HTMLElement, parameter: Parameter): ActionReturn<Parameter, Attributes> {
* // ...
* return {
* update: (updatedParameter) => {...},
* destroy: () => {...}
* };
* }
* ```
*
* Docs: https://svelte.dev/docs/svelte-action
*/
export interface ActionReturn<
Parameter = undefined,
Attributes extends Record<string, any> = Record<never, any>
> {
update?: (parameter: Parameter) => void;
destroy?: () => void;
/**
* ### DO NOT USE THIS
* This exists solely for type-checking and has no effect at runtime.
* Set this through the `Attributes` generic instead.
*/
$$_attributes?: Attributes;
}
/**
* Actions are functions that are called when an element is created.
* You can use this interface to type such actions.
* The following example defines an action that only works on `<div>` elements
* and optionally accepts a parameter which it has a default value for:
* ```ts
* export const myAction: Action<HTMLDivElement, { someProperty: boolean } | undefined> = (node, param = { someProperty: true }) => {
* // ...
* }
* ```
* `Action<HTMLDivElement>` and `Action<HTMLDivElement, undefined>` both signal that the action accepts no parameters.
*
* You can return an object with methods `update` and `destroy` from the function and type which additional attributes and events it has.
* See interface `ActionReturn` for more details.
*
* Docs: https://svelte.dev/docs/svelte-action
*/
export interface Action<
Element = HTMLElement,
Parameter = undefined,
Attributes extends Record<string, any> = Record<never, any>
> {
<Node extends Element>(
...args: undefined extends Parameter
? [node: Node, parameter?: Parameter]
: [node: Node, parameter: Parameter]
): void | ActionReturn<Parameter, Attributes>;
}
// Implementation notes:
// - undefined extends X instead of X extends undefined makes this work better with both strict and nonstrict mode