Question

我对节点和回调都很陌生。我正在研究Nodeschool问题：使用回调按顺序返回三个给定URL的数据。我将三个URL的结果放在一个对象中，以便按顺序跟踪它们。但是我一直在测试失败，因为我认为，在将所有URL放入其中之前，会返回URL对象。

TLDR：

这是违规功能。它一直告诉我＆＃34; SyntaxError：意外的令牌功能。＆＃34;但是当我将console.log(urlObj[url])放入自己的函数并在storeUrl中按名称调用它时，我认为它不是在if语句后运行的......

function storeUrl(url, info, function(url) {
    // Only log after all the checking is done
    console.log(urlObj[url]);
} ){
// add data to a dict? or something? 
// to keep track of them???
if(url == url1){
    urlObj[url1] = info;
}

if(url == url2){
    urlObj[url2] = info;
}

if(url == url3){
    urlObj[url3] = info;
}

}

这是我的整个文件：

var http = require('http');
var bl = require('bl');
var url1 = process.argv[2];
var url2 = process.argv[3];
var url3 = process.argv[4];
var urlObj = {};
urlObj[url1] = '';
urlObj[url2] = '';
urlObj[url3] = '';


function firstUrl(callback, callback){
    getHttp(url1);
    callback(url2);
    callback(url3);
}

function startItOff(){
    firstUrl(function secondUrl(contents){
    getHttp(contents);
    }, function thirdUrl(contents){
    getHttp(contents);
    });

    // This is what I ultimately want: 
    // A log of the data of each URL, in order, on its own line:
    for (item in urlObj){
        console.log(urlObj[item]);
    }
}

//////////////
// Above this line is ok,
// now trying to retrieve the url only after 
// getting the right one. The getHttp shows
// them in the right order, but retrieveHttp
// doesn't have an order to it.
/////////////

function getHttp(url){

    middleman(url, retrieveHttp);

}

function middleman(url, callback){
    callback(url);
}

function retrieveHttp(url){


    http.get(url, function(res){

    res.setEncoding('utf8');
    res.pipe(bl(function(err,data){
        if (err) return Error('Error');
        storeUrl(url, data.toString(), callback);

    }));

    });
}

function storeUrl(url, info, function(url) {
    console.log(urlObj[url]);
} ){
    // add data to a dict? or something? 
    // to keep track of them???
    if(url == url1){
    urlObj[url1] = info;
    }

    if(url == url2){
    urlObj[url2] = info;
    }

    if(url == url3){
    urlObj[url3] = info;
    }

    // Also trying to log the data from the URLs here:
    console.log(urlObj[url1]);

}

startItOff();

Answer 1

此行是语法错误：

function storeUrl(url, info, function(url) {
// Only log after all the checking is done -->

因此，当Node说出语法错误时，它不会说谎:)。当你定义函数的参数时，你就不能包含函数这个单词。

这将是有效的语法：

function storeUrl(url, info, callback) {
  console.log(url);
  callback();
}

我建议不要同时学习Node和Javascript。学习Javascript基础知识和调试，然后回调，然后解决Node。

节点回调中出现意外的令牌函数

1 个答案: