blocks|key|251133|text|process.nextTick将回调放入队列中。此队列中的每个回调都将在事件循环的下一个滴答开始时执行。它基本上被用作清除调用堆栈的一种方式。当文档中说它类似于setTimeout时，意思是说它类似于在浏览器中使用setTimeout(function()+{+...+},+1)。它有相同的用例。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|251134|一个示例用例是，您为一些需要绑定事件的对象创建一个构造函数。但是，您不能立即开始发出事件，因为实例化它的代码还没有时间绑定到事件。您的构造函数调用在调用堆栈中位于它们之上，如果您继续执行同步操作，它将保持这种方式。在这种情况下，您可以在继续执行任何操作之前使用process.nextTick。它保证使用你的构造函数的人有足够的时间来绑定事件。|251135|示例：|251136|var+MyConstructor+=+function()+{
++...
++process.nextTick(function()+{
++++self._continue();
++});
};

MyConstructor.prototype.__proto__+=+EventEmitter.prototype;

MyConstructor.prototype._continue+=+function()+{
++//+without+the+process.nextTick
++//+these+events+would+be+emitted+immediately
++//+with+no+listeners.+they+would+be+lost.
++this.emit('data',+'hello');
++this.emit('data',+'world');
++this.emit('end');
};|code-block|syntax|javascript|251137|使用此构造函数的示例中间件|251138|function(req,+res,+next)+{
++var+c+=+new+MyConstructor(...);
++c.on('data',+function(data)+{
++++console.log(data);
++});
++c.on('end',+next);
}|251139|entityMap^0|0|G|29|A|30|X|0|3M|G|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|14|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|15|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|16|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|17|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|T|$]]

<code>process.nextTick</code> puts a callback into a queue. Every callback in this queue will get executed at the very beginning of the next tick of the event loop. It's basically used as a way to clear your call stack. When the documentation says it's like <code>setTimeout</code>, it means to say it's like using <code>setTimeout(function() { ... }, 1)</code> in the browser. It has the same use cases.

One example use case would be, you create a constructor for some object that needs events bound to it. However, you can't start emitting events right away, because the code instantiating it hasn't had time to bind to events yet. Your constructor call is above them in the call stack, and if you continue to do synchronous things, it will stay that way. In this case, you could use a <code>process.nextTick</code> before proceeding to whatever you were about to do. It guarantees that the person using your constructor will have time enough to bind events.

Example:

<pre><code>var MyConstructor = function() {
 ...
 process.nextTick(function() {
 self._continue();
 });
};

MyConstructor.prototype.__proto__ = EventEmitter.prototype;

MyConstructor.prototype._continue = function() {
 // without the process.nextTick
 // these events would be emitted immediately
 // with no listeners. they would be lost.
 this.emit('data', 'hello');
 this.emit('data', 'world');
 this.emit('end');
};
</code></pre>

Example Middleware using this constructor

<pre><code>function(req, res, next) {
 var c = new MyConstructor(...);
 c.on('data', function(data) {
 console.log(data);
 });
 c.on('end', next);
}
</code></pre>

blocks|key|2925800|text|它只是在下一次I/O回调之前在当前操作结束时运行您的函数。Per+documentation你可以使用它在调用者同步代码执行后运行你的代码，如果你能用它让你的API/库用户有机会注册需要尽快发出的事件处理程序。另一个用例是确保您始终使用异步调用回调，以便在不同情况下具有一致的行为。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2925801|在过去，process.nextTick会被用来为I/O事件的执行提供机会，然而，这不再是这种行为，setImmediate是为这种行为而创建的。我解释了一个use+case+in+the+answer+of+this+question。|2925802|entityMap|0|LINK|mutability|MUTABLE|url|https://nodejs.org/api/all.html#process_process_nexttick_callback_args|1|https://stackoverflow.com/q/23672873/774086^0|T|H|0|0|27|13|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]|N|$5|I|J|K|C|$L|O]]]]

It simply runs your function at the end of the current operation before the next I/O callbacks. <a href="https://nodejs.org/api/all.html#process_process_nexttick_callback_args" rel="nofollow noreferrer">Per documentation</a> you can use it run your code after the callers synchronous code has executed, potentially if you can use this to give your API/library user an opportunity to register event handlers which need to be emitted ASAP. Another use case is to ensure that you always call the callbacks with asynchronously to have consistent behaviours in different cases.
In the past process.nextTick would be have been used provide an opportunities for I/O events to be executed however this is not the behaviour anymore and setImmediate was instead created for that behaviour. I explained a <a href="https://stackoverflow.com/q/23672873/774086">use case in the answer of this question</a>.

I have seen <a href="http://nodejs.org/docs/v0.3.1/api/process.html#process.nextTick" rel="noreferrer"><code>process.nextTick</code></a> used in a few places and can't quite tell what it's being used for.

<ul>
<li><a href="https://github.com/andrewvc/node-paperboy/blob/master/lib/paperboy.js#L24" rel="noreferrer">https://github.com/andrewvc/node-paperboy/blob/master/lib/paperboy.js#L24</a></li>
<li><a href="https://github.com/substack/node-browserify/blob/master/index.js#L95" rel="noreferrer">https://github.com/substack/node-browserify/blob/master/index.js#L95</a></li>
</ul>

What are the main/proper use cases of <code>process.nextTick</code> in Node.js? The docs basically say it's a more optimized way of doing <code>setTimeout</code>, but that doesn't help much.

I used to do a lot of ActionScript, so the idea of "waiting until the next frame" to execute code makes sense on some level - if you're running an animation you can have it update every frame rather than every millisecond for example. It also makes sense when you want to coordinate setting a bunch of variables - you change the variables in frame 1, and apply the changes in frame 2. Flex implemented something like this in their component lifecycle.

My question is, what should I be using this for in server-side JavaScript? I don't see any places right off the bat where you'd need this kind of fine-tuned performance/flow control. Just looking for a point in the right direction.

What are the proper use cases for process.nextTick in Node.js?

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我见过在一些地方使用，不太清楚它是用来做什么的。Node.js中process.nextTick的主要/适当用例是什么？文档基本上说这是一种更优化的setTimeout方式，但这并没有多大帮助。我曾经做过很多ActionScript，所以“等到下一帧”来执行代码的想法在某种程度上是有意义的--如果你正在运行一个动画，你...

问在Node.js中使用process.nextTick的正确用例是什么？
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