ComponentLink and Callbacks

The component "link" is the mechanism through which components are able to register callbacks and update themselves.

ComponentLink API


Registers a callback that will send a message to the component's update mechanism when it is executed. Under the hood, it will call send_self with the message that is returned by the provided closure. A Fn(IN) -> Vec<COMP::Message> is provided and a Callback<IN> is returned.


Sends a message to the component immediately after the current loop finishes, causing another update loop to initiate.


Registers a callback that sends a batch of many messages at once when it is executed. If any of the messages cause the component to re-render, the component will re-render after all messages in the batch have been processed. A Fn(IN) -> COMP::Message is provided and a Callback<IN> is returned.


(This might need its own short page.)

Callbacks are used to communicate with services, agents, and parent components within Yew. They are just a Fn wrapped by an Rc to allow them to be cloned.

They have an emit function that takes their <IN> type as an argument and converts that to a message expected by its destination. If a callback from a parent is provided in props to a child component, the child can call emit on the callback in its update lifecycle hook to send a message back to its parent. Closures or Functions provided as props inside the html! macro are automatically converted to Callbacks.