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我看了一些关于这个主题的其他问题,但是在这种情况下无法包装我的头如何实现它。Nodejs:比较两个异步请求的结果
我想实现:
- 访问网站,并获得内容(身体)
- 访问相匹配的测试网站,并获得内容(身体)
- 比较内容的第1页
- 抓取链接
- 第2页的抓取链接
- 继续
我目前遇到的问题是我无法比较内容,因为请求并未等待对方。 这是我的代码现在的样子。
require('colors');
var request = require('request');
var cheerio = require('cheerio');
var jsdiff = require('diff');
var URL = require('url-parse');
var PROD_START_URL = "https://www.somesite.org";
var MAX_PAGES_TO_VISIT = 100;
var pagesVisited = {};
var numPagesVisited = 0;
var pagesToVisit = [];
var globalProdContent;
var globalTestContent;
var url = new URL(PROD_START_URL);
var baseUrl = url.protocol + "//" + url.hostname;
pagesToVisit.push(PROD_START_URL);
crawl();
function crawl() {
if(numPagesVisited >= MAX_PAGES_TO_VISIT) {
console.log("Reached max limit of number of pages to visit.");
return;
}
var nextPage = pagesToVisit.pop();
if (nextPage in pagesVisited) {
// We've already visited this page, so repeat the crawl
crawl();
} else {
// New page we haven't visited
visitPage(nextPage, crawl);
}
}
function visitPage(url, callback) {
// Add page to our set
pagesVisited[url] = true;
numPagesVisited++;
// Make the request
console.log("Visiting page " + url);
request(url, function(error, response, body) {
// Check status code (200 is HTTP OK)
console.log("Status code: " + response.statusCode);
if(response.statusCode !== 200) {
callback();
return;
}
// Parse the document body
var $ = cheerio.load(body);
globalProdContent = $("#wrapper").text();
// Build new URL for test site
var testURL = url.replace("https://www.somesite.org", "http://matching.testsite");
// Scrape test site
scrapeTestContent(testURL);
collectInternalLinks($);
callback();
});
}
function collectInternalLinks($) {
var relativeLinks = [];
relativeLinks = $("a[href]");
console.log("Found " + relativeLinks.length + " relative links on page");
relativeLinks.each(function() {
pagesToVisit.push(baseUrl + "/" + $(this).attr('href'));
});
}
function scrapeTestContent(testURL) {
console.log("Visiting matching testpage " + testURL);
request(testURL, function(error, response, body) {
console.log("Status code: " + response.statusCode);
if(response.statusCode !== 200) {
callback();
return;
}
var $ = cheerio.load(body);
globalTestContent = $("#wrapper").text();
console.log(globalTestContent);
});
}
有没有更简单的方法来做到这一点,还是我完全脱离轨道?