在JavaScript中，处理程序将按什么顺序执行？

如何解决在JavaScript中，处理程序将按什么顺序执行？

给我的印象是then处理函数按其添加顺序进行处理。

例如，如果您运行以下代码：

function getResolvedPromise(result) {
  return new Promise((resolve,reject) => {
    console.log(`Promise executor,result will be ${result}`);
    resolve(result);
  });
}

function logThen(label,result) {
  console.log(`[${label}] Promise then,result = ${result}`);
  return result;
}

// Shows that then handlers get run in the order they are added.

const prom1 = getResolvedPromise("prom1");
const prom2 = getResolvedPromise("prom2");

prom2.then(logThen.bind(null,"1"));
prom2.then(logThen.bind(null,"2"));
prom2.then(logThen.bind(null,"3"));

prom1.then(logThen.bind(null,"4"));
prom1.then(logThen.bind(null,"5"));
prom1.then(logThen.bind(null,"6"));

这就是要记录的内容。这对我来说很有意义。

Promise executor,result will be prom1
Promise executor,result will be prom2
[1] Promise then,result = prom2
[2] Promise then,result = prom2
[3] Promise then,result = prom2
[4] Promise then,result = prom1
[5] Promise then,result = prom1
[6] Promise then,result = prom1

但是，如果运行此命令：

// Order of execution is interleaved when then handlers are directly attached?

const prom1 = getResolvedPromise("prom1")
  .then(logThen.bind(null,"1"))
  .then(logThen.bind(null,"2"))
  .then(logThen.bind(null,"3"));

const prom2 = getResolvedPromise("prom2")
  .then(logThen.bind(null,"4"))
  .then(logThen.bind(null,"5"))
  .then(logThen.bind(null,"6"));

这就是要记录的内容。

Promise executor,result = prom1
[4] Promise then,result = prom2

什么解释了这种交错行为？

请注意，规范包含一些相关信息here。具体来说，它是关于HostEnqueuePromiseJob的：

作业必须以与安排它们的HostEnqueuePromiseJob调用相同的顺序运行。

如果我们查看specification for Promise.prototype.then，我们会看到它调用了HostEnqueuePromiseJob。因此，这对我来说唯一有意义的方法是按交错顺序调用then调用。但是...我真的不知道怎么回事，因为我发布的两个代码示例似乎与我等效。