Interface Options

Additional options for a listener.

interface Options {
once?: boolean;
transactional?: boolean;
}

Properties

once?: boolean

If true, the listener will be removed after the first time it is called.

false;

transactional?: boolean

Whether the listener takes part in the operation that notifies it.

true when the listener is added during an operation - a listener added as a consequence of one is part of it - and false otherwise.

A transactional listener:

is told inline, inside the operation, so anything it writes joins that same commit, and is told during an undo or a redo for the same reason;
hears nothing announced outside an operation;
is part of the document: the operation that added it removes it on undo and puts it back on redo.

A non-transactional listener:

is told once per operation, after it has landed, however many times the operation notified, and not at all if the operation is rolled back;
is told at once when there is no operation, and at once during an undo or a redo;
survives an undo, since it is not part of the document.