如何知道什么时候递归，异步任务完成 [英] How to know when a recursive, asynchronous task finishes
问题描述
我有一个异步功能，即可以递归到自身。
I have a async function, which can recurse into itself.
我在每个函数运行时间增加的jQuery deferreds到一个数组，一个使用 $。当（）来检查是否所有的承诺都解决了。我的问题是，我似乎无法做到这一点没有arbitary超时，因为我根本不知道什么时候停止功能递归和增加新的承诺。
I'm adding jQuery deferreds to an array each time the function runs, an use $.when() to check if all promises have resolved. My issue is that I can't seem to do this without an arbitary timeout, as I simply don't know when the function stops recursing and adding new promises.
- Here's a JSBin demonstration.
- And here's the real world example.
推荐答案
不要推到承诺只有同步，让你知道当你完成。由于你的函数是递归，并返回一个承诺，你可以使用这个递归调用的结果的承诺。使用 $。当（）只为结果的的电流的递归级别，而不是调用堆栈的所有承诺。
Do push to promises only synchronously, so that you know when you are finished. Since your function is recursive and returns a promise, you can just use the result promises of the recursive calls for this. Use $.when() only for the results of the current recursion level, not for all promises in the call stack.
还检查我的回答了解承诺在node.js中的递归函数并的Is有使用原始Q承诺库节点递归遍历目录异步的例子 - 即使他们没有使用jQuery的实现，他们应该给你一个想法如何做到这一点。
Also check my answers to Understanding promises in node.js for recursive function and Is there an example of using raw Q promise library with node to recursively traverse a directory asynchronously? - even though they're not using jQuery's implementation, they should give you an idea of how to do it.
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