Question

为什么setTimeout如此无效？

我有100个任务，每个任务需要1毫秒。我将它们与requestAnimationFrame交错，它应该在16ms左右。所以，我希望看到每个rAF执行这些任务中的14-16个。相反，我看到每个rAF 1-3。

var count = 0;
var limit = 100;

function doSomething1ms() {
  var start = performance.now();
  while (performance.now() - start < 1);
  log("finished: " + count);
  if (++count < limit) {
    setTimeout(doSomething1ms, 0);
  }
}
doSomething1ms();
  
var rafCount = 100;
function raf() {
  log("raf");
  --rafCount;
  if (rafCount) {
    requestAnimationFrame(raf);
  }
};
requestAnimationFrame(raf);

log("start------------------------");

function log(msg) {
  var div = document.createElement('div');
  div.appendChild(document.createTextNode(msg));
  document.body.appendChild(div);
}

Answer 1

根据bergi的评论和链接，setTimeout的限制为4毫秒

使用postMessage我每个rAF可以获得7-10个电话，虽然距离很远，但仍然很好。

＆＃13;

var count = 0;
var limit = 100;

function doSomething1ms() {
  var start = performance.now();
  while (performance.now() - start < 1);
  log("finished: " + count);
  queueNext();
}

window.addEventListener('message', doSomething1ms);

function queueNext() {
  if (++count < limit) {
    window.postMessage({}, "*", []);
  }
}
queueNext();
  
var rafCount = 100;
function raf() {
  log("raf");
  --rafCount;
  if (rafCount) {
    requestAnimationFrame(raf);
  }
};
requestAnimationFrame(raf);

log("start------------------------");

function log(msg) {
  var div = document.createElement('div');
  div.appendChild(document.createTextNode(msg));
  document.body.appendChild(div);
}

＆＃13;

为什么setTimeout如此不具有性能

1 个答案: