使用async需要异步功能，但我的功能是异步的 [英] Using async requires async function, but my function is async

问题描述

我正在调整使用回调的库以使用Promises。它在我使用 then（）时工作，但是当我使用 await 时它不起作用。

I'm adapting a library that uses callback to use Promises. It's working when I use then(), but it doesn't work when I use await.

> dbc.solve
[AsyncFunction]
> await dbc.solve(img)
await dbc.solve(img)
^^^^^

SyntaxError: await is only valid in async function

dbc.solve的代码是：

The code for dbc.solve is:

module.exports = DeathByCaptcha = (function() {
  function DeathByCaptcha(username, password, endpoint) {
    ...
  }

  DeathByCaptcha.prototype.solve = async function(img) {
    return new Promise(
      function(resolve, reject) {
        ...
      }
    );
  };
})();

我相信这有事实 solve 是 prototype 的成员，但我找不到任何有关它的信息。我发现节点没有始终支持异步等待类方法，所以我升级了从节点7开始，现在我正在使用节点9.4.0。

I believe this has something with the fact solve is member of prototype, but I couldn't find any information about it. I found that node didn't always supported async await for class methods, so I upgraded from node 7, now I'm using node 9.4.0.

推荐答案

您没有正确阅读该错误消息：问题不在于您正在调用的功能，而是 中的功能。

You don't read that error message right: the problem isn't the function you're calling but the function you're in.

您可以

(async function(){
    await dbc.solve(img);
    // more code here or the await is useless
})();

请注意，节点的REPL中不再需要这个技巧了： https://github.com/nodejs/node/issues/13209

Note that this trick should soon enough not be needed anymore in node's REPL: https://github.com/nodejs/node/issues/13209

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