count

count(proxied): ValueRef<number>

Defined in: aberdeen.ts:1280

Reactively counts the number of properties in an object.

Parameters

proxied

TargetType

The observable object to count. In case an array, Map, or Set is passed in, a ref to its .length or .size will be returned.

Returns

ValueRef<number>

an observable object for which the value property reflects the number of properties in proxied with a value other than undefined, or the collection size for arrays, Maps, and Sets.

Example

const $items = A.proxy({x: 3, y: 7} as any);
const $count = A.count($items);

// Create a DOM text node for the count:
A('div text=', $count);
// <div>2</div>

// Or we can use it in an {@link derive} function:
A(() => console.log("The count is now", $count.value));
// The count is now 2

// Adding/removing items will update the count
$items.z = 12;
// Asynchronously, after 0ms:
// <div>3</div>
// The count is now 3