如何等待Node.js [英] How to Wait in Node.js

问题描述

这里是一个关于我认为在节点js中的简单模式的问题。

Here is a question about what I would think would be a simple pattern in node js.

这是我在coffeescript中的示例：

Here is my example in coffeescript:

db_is_open = false

db.open ->
  db_is_open = true

wait = ->
wait() until db_is_open

再次在javascript中：

And here again in javascript:

var db_is_open = false;

db.open(function() {
  db_is_open = true;
});

function wait() {};
while (not db_is_open) { wait()};

这根本不工作，因为while循环从不放弃控制，我猜这是有意义的。但是如何告诉等待函数来尝试队列中的下一个回调呢？

This does not work at all because the while loop never relinquishes control, which I guess makes sense. However how can I tell the wait function to try the next callback in the queue?

推荐答案

为什么要等待，使用在传递给 db.open 的函数内部运行的回调？这是几乎成语节点代码：

Why are you waiting, and not just using a callback that runs inside of the function passed to db.open? This is pretty much idiomatic Node code:

db.open(function() {
  // db is now open, let's run some more code
  execute_db_query();
});

基本上，你应该遵循文档。

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