Question

我基本上想要做的就是能够使用异步函数的返回值。我假设变量标签（在下面的代码中）将包含来自异步函数的返回值，但它包含响应。我怎么可能把aRes函数的返回值保存到一个我可以在异步函数范围之外使用的变量中。提前谢谢。

var http = require('http');
var url = "someurl.com"

//async function to be passed to http.get as second parameter
function aRes(response){
    var newtag = response.headers.etag;
    return newtag;
}

var tag = http.get(url,aRes);
console.log(tag); //logs the response from get request

//tag is not the return value from the ares function but rather the response object. How do I get the return value of that?

Answer 1

使用回调。或者更好地使用Promise（建议尝试addresses = geocoder.getFromLocation(lat, lon, 1); if (addresses != null && !addresses.isEmpty()) { String address = addresses.get(0).getAddressLine(0); String city = addresses.get(0).getLocality(); String state = addresses.get(0).getAdminArea(); String country = addresses.get(0).getCountryName(); String postalCode = addresses.get(0).getPostalCode(); String knownName = addresses.get(0).getFeatureName(); }），您的代码看起来会更容易阅读。

在宣传之后，您可以使用bluebird库执行以下操作。

request

request.getAsync(url) .spread(yourFunction)将从yourFunction获取args。

Answer 2

创建自己的回调函数：

var http = require('http');
var url = "someurl.com";

var aResCallback = function(tag) {
    console.log(tag); //logs the response from get request
};

//async function to be passed to http.get as second parameter
function aRes(response){
    var newtag = response.headers.etag;
    aResCallback(newtag);
    return newtag;
}

var tag = http.get(url, aRes);

如何在Node JS中返回异步函数的值并在范围之外使用

2 个答案: