javascript - learnyounode #9 杂耍异步

Question

我正在尝试学习 nodeschool 的 learnyounode。

This problem is the same as the previous problem (HTTP COLLECT) in that you need to use http.get(). However, this time you will be provided with three URLs as the first three command-line arguments.

You must collect the complete content provided to you by each of the URLs and print it to the console (stdout). You don't need to print out the length, just the data as a String; one line per URL. The catch is that you must print them out in the same order as the URLs are provided to you as command-line arguments.

我对为什么我的解决方案不能正常工作感到困惑，因为它对我来说看起来一样，但功能更强大，而且我不确定他们的内部测试工作原理:

1.  ACTUAL:    ""
1.  EXPECTED:  "As busy as a dead horse also lets get some dero. Built like a sleepout no dramas lets get some chook. She'll be right thingo my she'll be right ute. "

2.  ACTUAL:    "She'll be right bizzo no worries she'll be right fair dinkum. We're going aerial pingpong no worries as busy as a gyno. "
2.  EXPECTED:  "She'll be right bizzo no worries she'll be right fair dinkum. We're going aerial pingpong no worries as busy as a gyno. "

3.  ACTUAL:    "He's got a massive pretty spiffy heaps she'll be right brizzie. He hasn't got a fly wire where shazza got us some strewth. She'll be right spit the dummy with it'll be fair go. We're going gobsmacked with as stands out like arvo. He's got a massive bush bash mate she'll be right slacker. "
3.  EXPECTED:  "He's got a massive pretty spiffy heaps she'll be right brizzie. He hasn't got a fly wire where shazza got us some strewth. She'll be right spit the dummy with it'll be fair go. We're going gobsmacked with as stands out like arvo. He's got a massive bush bash mate she'll be right slacker. "

4.  ACTUAL:    ""
4.  EXPECTED:  ""

我的代码:

var http = require('http');
var bl = require('bl');

var result = [];
var urls = process.argv.slice(2);
urls.forEach(function(url, i) {
  http.get(url, function(response) {
    response.pipe(bl(function(err, data) {
      if (err) return console.error(err);
      result[i] = data.toString();
      if (i === urls.length - 1) {
        console.log(result.join('\n'));
      }
    }));
  });
});

官方解决方案:

var http = require('http')
var bl = require('bl')
var results = []
var count = 0

function printResults () {
  for (var i = 0; i < 3; i++)
    console.log(results[i])
}

function httpGet (index) {
  http.get(process.argv[2 + index], function (response) {
    response.pipe(bl(function (err, data) {
      if (err)
        return console.error(err)

      results[index] = data.toString()
      count++

      if (count == 3)
        printResults()
    }))
  })
}

for (var i = 0; i < 3; i++)
  httpGet(i)

基本上第一个测试永远不会通过(尽管如果迭代数组中只有 1 个 url(而不是 3 个)，第一个测试通过但其他测试不通过)。任何见解都会很棒。我不确定在哪里问这个问题，也许我只是遗漏了一些 JS 的东西，如果这不合适，我很抱歉。

Answer 1

您尚未确定是否已下载所有网址。

请求不一定按顺序返回。考虑3是否先回来。您将跳过其他两个 url，只打印出 3 个。

演示代码计算响应的数量，因此可以保证在打印出答案之前得到所有信息。