promise打印顺序问题

发布于
2022-03-20

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>promise</title>
</head>
<body>
  <script>
    let p = new Promise((resolve, reject) => {
      resolve('done')
    })

    const res = p.then(value => {
      console.log(value)
    }, reason => {
      console.warn(reason)
    })

    console.log(res)
  </script>
</body>
</html>

为什么控制台先打印res再打印value呢？代码都是同步的，不应该从上往下依次执行嘛？