requestHostCallback

MessageChannelを使ってperformWorkUntilDeadlineを実行させる。unstable_scheduleCallbackで呼ばれる。

code:js

function requestHostCallback(callback) {

scheduledHostCallback = callback;

if (!isMessageLoopRunning) {

isMessageLoopRunning = true;

schedulePerformWorkUntilDeadline();

}

// DOM and Worker environments.

// We prefer MessageChannel because of the 4ms setTimeout clamping.

const channel = new MessageChannel();

const port = channel.port2;

channel.port1.onmessage = performWorkUntilDeadline;

const schedulePerformWorkUntilDeadline = () => {

port.postMessage(null);

};