npm package: @solid-primitives/active-element
Description: A reactive document.activeElement. Check which element is currently focused.
Author: Damian Tarnawski @thetarnav
Latest version: 2.1.5

<p>
  <img width="100%" src="https://assets.solidjs.com/banner?type=Primitives&background=tiles&project=Active%20Element" alt="Solid Primitives Active Element">
</p>

# @solid-primitives/active-element

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##### Non-reactive primitives:

- [`makeActiveElementListener`](#makeactiveelementlistener) - Listen for changes to the `document.activeElement`.
- [`makeFocusListener`](#makefocuslistener) - Attaches "blur" and "focus" event listeners to the element.

##### Reactive primitives:

- [`createActiveElement`](#createactiveelement) - Provides reactive signal of `document.activeElement`.
- [`createFocusSignal`](#createfocussignal) - Provides a signal representing element's focus state.

##### Directives:

- [`focus`](#focus) - A directive that notifies you when the element becomes active or inactive.

## Installation

```bash
npm install @solid-primitives/active-element
# or
yarn add @solid-primitives/active-element
```

## `makeActiveElementListener`

###### Added id `@2.0.0`

Attaches event listeners to window, listening for the changes of the `document.activeElement`.

```ts
import { makeActiveElementListener } from "@solid-primitives/active-element";

const [activeElement, setActiveElement] = createSignal(null);
const clear = makeActiveElementListener(el => setActiveElement(el));

// remove listeners (happens also on cleanup)
clear();
```

#### Definition

```ts
function makeActiveElementListener(callback: (element: Element | null) => void): VoidFunction;
```

## `makeFocusListener`

###### Added id `@2.0.0`

Attaches "blur" and "focus" event listeners to the element.

```ts
import { makeFocusListener } from "@solid-primitives/active-element";

const [isFocused, setIsFocused] = createSignal(false);
const clear = makeFocusListener(focused => setIsFocused(focused));

// remove listeners (happens also on cleanup)
clear();
```

#### Definition

```ts
function makeFocusListener(
  target: Element,
  callback: (isActive: boolean) => void,
  useCapture?: boolean,
): VoidFunction;
```

## `createActiveElement`

Provides reactive signal of `document.activeElement`. Check which element is currently focused.

#### How to use it

```ts
import { createActiveElement } from "@solid-primitives/active-element";

const activeEl = createActiveElement();

createEffect(() => {
  console.log(activeEl()); // T: Element | null
});
```

#### Definition

```ts
function createActiveElement(): Accessor<Element | null>;
```

## `createFocusSignal`

Provides a signal representing element's focus state.

#### How to use it

```tsx
import { createFocusSignal } from "@solid-primitives/active-element";

const isFocused = createFocusSignal(el);
isFocused(); // T: boolean

// you can also use signals for ref
const [ref, setRef] = createSignal<Element>(el);
const isFocused = createFocusSignal(ref);
// this way if the element changes,
// the "isFocused" will start checking the new element

// is targeting a ref from jsx, pass it as a function
// or wrap primitive in onMount, so that it is accessed once mounted
let ref;
createFocusSignal(() => ref);
<div ref={ref} />;
```

#### Definition

```ts
function createFocusSignal(target: MaybeAccessor<Element>): Accessor<boolean>;
```

## `focus`

A directive that notifies you when the element becomes active or inactive.

```tsx
const [active, setActive] = createSignal(false)
<input use:focus={setActive} />
```

#### Definition

```ts
Directive<(isActive: boolean) => void>;
```

## Demo

https://codesandbox.io/s/solid-primitives-active-element-q4kul?file=/index.tsx

## Changelog

See [CHANGELOG.md](./CHANGELOG.md)