像这样的东西在异步代码中工作吗？

发布于 2024-11-09 01:16:38 字数 523 浏览 0 评论 0原文

regular = 'a string';
enriched = enrichString(regular);
sys.puts(enriched);

function enrichString(str){
    //run str through some regex stuff or other string manipulations
    return str;
}

现在它似乎正在做我希望它做的事情，但我不知道它是否安全。有时这会导致未定义吗？我需要做这样的事情吗：

regular = 'a string';
enriched = enrichString(regular, function(data){sys.puts(data);});

function enrichString(str, cb){
    //run str through some regex stuff or other string manipulations
    cb(str);
}

谢谢您的帮助！

原文

regular = 'a string';
enriched = enrichString(regular);
sys.puts(enriched);

function enrichString(str){
    //run str through some regex stuff or other string manipulations
    return str;
}

Right now it seems to be doing what I hoped it would do but I don't know if its safe. Could this result in undefined sometimes? Do I need to do something like:

regular = 'a string';
enriched = enrichString(regular, function(data){sys.puts(data);});

function enrichString(str, cb){
    //run str through some regex stuff or other string manipulations
    cb(str);
}

Thanks for the help!

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甜｀诱少女 2024-11-16 01:16:38

不，你应该没问题。计算代码的直接运行本质上不是异步的。当某些操作涉及外部资源（文件 I/O、网络操作、某些操作系统交互等）时，需要回调。

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絕版丫頭 2024-11-16 01:16:38

如果您进行异步非阻塞调用，则仅需要回调。

var string = "foo",
    new_string = enrich(foo);

doStuff(new_string);

如果 enrich 被阻塞，则安全。例如

function enrich(str) {
    // do regex stuff with str

    // manipulate it

    return str;
}

阻塞，所以这样做是安全的。其中 as

function enrich(str) {
    // get some data from the database.

    // store the string in a file.

    return str;
}

使用非阻塞 IO 并且不安全。您想要做的是这样的：

function enrich(str, cb) {
    // get some data from the database.

    // store the string in a file.

    return cb(str);
}

var string = "foo",
    new_string = enrich(foo, function (str) {
        doStuff(new_string);
    });

请注意

enriched = richString(regular, sys.puts(data));

不起作用，因为您传入了 sys.puts(data ) 作为函数参数（数据也未定义！）

您需要传入一个函数。

You only need callbacks if your making asychronous non-blocking calls.

var string = "foo",
    new_string = enrich(foo);

doStuff(new_string);

Is safe if enrich is blocking. For example

function enrich(str) {
    // do regex stuff with str

    // manipulate it

    return str;
}

is blocking so it's safe to do this. Where as

function enrich(str) {
    // get some data from the database.

    // store the string in a file.

    return str;
}

Uses non blocking IO and is not safe. What you want to do is this :

function enrich(str, cb) {
    // get some data from the database.

    // store the string in a file.

    return cb(str);
}

var string = "foo",
    new_string = enrich(foo, function (str) {
        doStuff(new_string);
    });

Notice that

enriched = enrichString(regular, sys.puts(data));

Does not work because your passing in the return value of sys.puts(data) as your function parameter (data is undefined aswell!)

You need to pass in a function.

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抠脚大汉 2024-11-16 01:16:38

只是为了添加 Pointy 的响应，人们有时会使用 process.nextTick （或在浏览器中 setTimeout(fn,0)）强制异步行为 - 这会强制当前执行上下文屈服。例如： https://github.com/caolan/async /blob/master/lib/async.js#L408-410

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