server.listen()的异步而不是then()

async-await 行为与……相似 .then() await .然后() 继续承诺和决心 .catch() 拒绝承诺。

foo().then( function(result){}); // got result here
result = await foo(); // will get same result here too as in above function.

同样地 catch(err) 在里面 try-catch .catch( function(err) {}) 在里面 .then()-.catch() .

async-await here 和 here .

(async function () {
    try {
        const { url } = await server.listen(port);
        console.log(`Server ready at ${url}`);
    } catch(e) {
        // handle errors
    }
})();      // This is [IIFE][3]. In this case it's better to have IIFE then regular function, as functions needed to be called.

异步等待作为一个函数:

async function startServer() {
    try {
        const { url } = await server.listen(port);
        console.log(`Server ready at ${url}`);
    } catch(e) {
        // handle errors
    }
}

startServer();    // Not an IIFE

包含在 async . 那么,怎么办呢 .then server.listen ,你会的 await server.listen(... 相反:

async function foo() {
  // ...
  const { url } = await server.listen(port);
  console.log(`Server ready at ${url}`);
}

foo :

foo()
  .catch((err) => {
    // handle errors
  });

catch 福 :

async function foo() {
  try {
    const { url } = await server.listen(port);
    console.log(`Server ready at ${url}`);
  } catch(e) {
    // handle errors
  }
}

你必须 await 返回 ,不要退回回回调样式:

 (async function () {
    const url = await server.listen(port);
    console.log(`Server listening at "${url}"`);
 })();