域和 promise

🌐 Domains and promises

从 Node.js 8.0.0 开始，Promise 的处理程序会在调用 .then() 或 .catch() 时所在的域中执行：

🌐 As of Node.js 8.0.0, the handlers of promises are run inside the domain in which the call to .then() or .catch() itself was made:

const d1 = domain.create();
const d2 = domain.create();

let p;
d1.run(() => {
  p = Promise.resolve(42);
});

d2.run(() => {
  p.then((v) => {
    // running in d2
  });
}); 拷贝

可以使用 domain.bind(callback) 将回调绑定到特定域：

🌐 A callback may be bound to a specific domain using domain.bind(callback):

const d1 = domain.create();
const d2 = domain.create();

let p;
d1.run(() => {
  p = Promise.resolve(42);
});

d2.run(() => {
  p.then(p.domain.bind((v) => {
    // running in d1
  }));
}); 拷贝

域不会干扰 Promise 的错误处理机制。换句话说，对于未处理的 Promise 拒绝，不会触发任何 'error' 事件。

🌐 Domains will not interfere with the error handling mechanisms for promises. In other words, no 'error' event will be emitted for unhandled Promise rejections.