@domgell/defer v1.0.2

defer

The using keyword and [Symbol.dispose] can be used to automatically call a function at the end of the current scope.

Example

Defer() creates an object with the [Symbol.dispose] property. At the end of the scope, it will call all callbacks (in reverse order).

using defer = Defer();
 
const file = openFile();
defer(() => file.close());
... 
// `file.close()` is called at the end of the scope

deferred(obj, fn) attaches [Symbol.dispose] to an existing object and calls the callback at the end of the scope.

using file = deferred(openFile(), f => f.close());
...
// `f.close()` is called at the end of the scope

With the using keyword, everything is cleaned up in reverse order. This is also implemented for Defer(), where callbacks are called in reverse order.

// Prints '1, 2, 3' at the end of the scope
using defer = Defer();
defer(() => console.log(3))
defer(() => console.log(2))
defer(() => console.log(1))