问题
What is the most straight-forward and direct way to queue a task in the browser event loop, using JavaScript?
Things that don't work:
- window.setImmediate(func): Non-standard.
window.setTimeout(func, 0)
/window.setInterval(func, 0)
: Browsers throttle timers to ≥ 4ms.new Promise(r => r()).then(func)
: That queues a microtask, not a task.
回答1:
MessagePort.postMessage does just that.
onmessage = e => handleMessage;
postMessage("","*");
You can even use a MessageChannel if you want a less intrusive mean:
const channel = new MessageChannel();
channel.port1.onmessage = handleMessage;
channel.port2.postMessage('');
This is currently the only API that does queue a task synchronously, all others implying at least some in parallel execution.
Maybe one day we will have a scheduler.postTask method, which would even allow us to specify some priority for our tasks, but that's for the future only...
来源:https://stackoverflow.com/questions/61574088/how-to-queue-a-macrotask-in-the-javascript-task-queue