I am trying to build a module that does some basic scraping on an official NBA box score page (e.g. https://stats.nba.com/game/0021800083) using request-promise and cheerio. I wrote the following test code:
const rp = require("request-promise");
const co = require("cheerio");
// the object to be exported
var stats = {};
const test = (gameId) => {
rp(`http://stats.nba.com/game/${gameId}`)
.then(response => {
const $ = co.load(response);
$('td.player').each((i, element) => {
console.log(element);
});
});
};
// TESTING
test("0021800083");
module.exports = stats;
When I inspect the test webpage, there are multiple instances of td tags with class="player", but for some reason selecting them with cheerio doesn't work.
But cheerio does successfully select some elements, including a, script and div tags.
Help would be appreciated!
Using a scraper like request-promise will not work for a site built with AngularJS. Your response does not consist of the rendered HTML, as you are probably expecting. You can confirm by console logging the response. In order to properly scrape this site you could use PhantomJS, Selenium Webdriver, and the like.
An easier approach is to identify the AJAX call that is providing the data your are after and scrape that instead. For this, go to the site and in the developer tools, open the Network tab. Look at the list of requests and identify which one has the data you are after.
Assuming you are after the player stats in the tables, the one I believe you are looking for is "0021800083_gamedetail.json"
Further reading:
Can you scrape a Angular JS website
Scraping Data from AngularJS loaded page
Best of luck!
I want to scrape my college website (moodle) with node.js but I haven't found a headless browser able to do it. I have done it in python in just 10 lines of code using RoboBrowser:
from robobrowser import RoboBrowser
url = "https://cas.upc.edu/login?service=https%3A%2F%2Fatenea.upc.edu%2Fmoodle%2Flogin%2Findex.php%3FauthCAS%3DCAS"
browser = RoboBrowser()
browser.open(url)
form = browser.get_form()
form['username'] = 'myUserName'
form['password'] = 'myPassword'
browser.submit_form(form)
browser.open("http://atenea.upc.edu/moodle/")
print browser.parsed
The problem is that the website requires authentication. Can you help me? Thanks!
PD: I think this can be useful https://www.npmjs.com/package/form-scraper but I can't get it working.
Assuming you want to read a 3rd party website, and 'scrape' particular pieces of information, you could use a library such as cheerio to achieve this in Node.
Cheerio is a "lean implementation of core jQuery designed specifically for the server". This means that given a String representation of a DOM (or part thereof), cheerio can traverse it in much the same way as jQuery can.
An example from Max Ogden show how you can use the request module to grab HTML from a remote server and then pass it to cheerio:
var $ = require('cheerio')
var request = require('request')
function gotHTML(err, resp, html) {
if (err) return console.error(err)
var parsedHTML = $.load(html)
// get all img tags and loop over them
var imageURLs = []
parsedHTML('a').map(function(i, link) {
var href = $(link).attr('href')
if (!href.match('.png')) return
imageURLs.push(domain + href)
})
}
var domain = 'http://substack.net/images/'
request(domain, gotHTML)
Selenium has support for multiple languages and multiple platforms and multiple browsers.
How can you use Javascript to parse out the URL of a page?
First of all, you have to decide whether you want to do this on the client or on the server. On the server, you can load the XML and use XPath to locate the part of the XML DOM tree that contains the site:
//site/name[text() = 'Blah00']
When using JavaScript on the client, a better solution would be to have a server which keeps the current status per site (use a database or some in-memory structure). Then use AJAX requests to ask the server for the information for a certain site. jQuery will make your life much easier.
I have solved this:
<script>
function mySiteURL() {
var myURL = window.location.href;
var dashIndex = myURL.lastIndexOf("-");
var dotIndex = myURL.lastIndexOf(".");
var result = myURL.substring(dashIndex + 1, dotIndex);
}
</script>
I want to crawl the page and check for the hyperlinks in that respective page and also follow those hyperlinks and capture data from the page
Generally, browser JavaScript can only crawl within the domain of its origin, because fetching pages would be done via Ajax, which is restricted by the Same-Origin Policy.
If the page running the crawler script is on www.example.com, then that script can crawl all the pages on www.example.com, but not the pages of any other origin (unless some edge case applies, e.g., the Access-Control-Allow-Origin header is set for pages on the other server).
If you really want to write a fully-featured crawler in browser JS, you could write a browser extension: for example, Chrome extensions are packaged Web application run with special permissions, including cross-origin Ajax. The difficulty with this approach is that you'll have to write multiple versions of the crawler if you want to support multiple browsers. (If the crawler is just for personal use, that's probably not an issue.)
If you use server-side javascript it is possible.
You should take a look at node.js
And an example of a crawler can be found in the link bellow:
http://www.colourcoding.net/blog/archive/2010/11/20/a-node.js-web-spider.aspx
Google's Chrome team has released puppeteer on August 2017, a node library which provides a high-level API for both headless and non-headless Chrome (headless Chrome being available since 59).
It uses an embedded version of Chromium, so it is guaranteed to work out of the box. If you want to use an specific Chrome version, you can do so by launching puppeteer with an executable path as parameter, such as:
const browser = await puppeteer.launch({executablePath: '/path/to/Chrome'});
An example of navigating to a webpage and taking a screenshot out of it shows how simple it is (taken from the GitHub page):
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://example.com');
await page.screenshot({path: 'example.png'});
await browser.close();
})();
We could crawl the pages using Javascript from server side with help of headless webkit. For crawling, we have few libraries like PhantomJS, CasperJS, also there is a new wrapper on PhantomJS called Nightmare JS which make the works easier.
There are ways to circumvent the same-origin policy with JS. I wrote a crawler for facebook, that gathered information from facebook profiles from my friends and my friend's friends and allowed filtering the results by gender, current location, age, martial status (you catch my drift). It was simple. I just ran it from console. That way your script will get privilage to do request on the current domain. You can also make a bookmarklet to run the script from your bookmarks.
Another way is to provide a PHP proxy. Your script will access the proxy on current domain and request files from another with PHP. Just be carefull with those. These might get hijacked and used as a public proxy by 3rd party if you are not carefull.
Good luck, maybe you make a friend or two in the process like I did :-)
My typical setup is to use a browser extension with cross origin privileges set, which is injecting both the crawler code and jQuery.
Another take on Javascript crawlers is to use a headless browser like phantomJS or casperJS (which boosts phantom's powers)
This is what you need http://zugravu.com/products/web-crawler-spider-scraping-javascript-regular-expression-nodejs-mongodb
They use NodeJS, MongoDB and ExtJs as GUI
yes it is possible
Use NODEJS (its server side JS)
There is NPM (package manager that handles 3rd party modules) in nodeJS
Use PhantomJS in NodeJS (third party module that can crawl through websites is PhantomJS)
There is a client side approach for this, using Firefox Greasemonkey extention. with Greasemonkey you can create scripts to be executed each time you open specified urls.
here an example:
if you have urls like these:
http://www.example.com/products/pages/1
http://www.example.com/products/pages/2
then you can use something like this to open all pages containing product list(execute this manually)
var j = 0;
for(var i=1;i<5;i++)
{
setTimeout(function(){
j = j + 1;
window.open('http://www.example.com/products/pages/ + j, '_blank');
}, 15000 * i);
}
then you can create a script to open all products in new window for each product list page and include this url in Greasemonkey for that.
http://www.example.com/products/pages/*
and then a script for each product page to extract data and call a webservice passing data and close window and so on.
I made an example javascript crawler on github.
It's event driven and use an in-memory queue to store all the resources(ie. urls).
How to use in your node environment
var Crawler = require('../lib/crawler')
var crawler = new Crawler('http://www.someUrl.com');
// crawler.maxDepth = 4;
// crawler.crawlInterval = 10;
// crawler.maxListenerCurrency = 10;
// crawler.redisQueue = true;
crawler.start();
Here I'm just showing you 2 core method of a javascript crawler.
Crawler.prototype.run = function() {
var crawler = this;
process.nextTick(() => {
//the run loop
crawler.crawlerIntervalId = setInterval(() => {
crawler.crawl();
}, crawler.crawlInterval);
//kick off first one
crawler.crawl();
});
crawler.running = true;
crawler.emit('start');
}
Crawler.prototype.crawl = function() {
var crawler = this;
if (crawler._openRequests >= crawler.maxListenerCurrency) return;
//go get the item
crawler.queue.oldestUnfetchedItem((err, queueItem, index) => {
if (queueItem) {
//got the item start the fetch
crawler.fetchQueueItem(queueItem, index);
} else if (crawler._openRequests === 0) {
crawler.queue.complete((err, completeCount) => {
if (err)
throw err;
crawler.queue.getLength((err, length) => {
if (err)
throw err;
if (length === completeCount) {
//no open Request, no unfetcheditem stop the crawler
crawler.emit("complete", completeCount);
clearInterval(crawler.crawlerIntervalId);
crawler.running = false;
}
});
});
}
});
};
Here is the github link https://github.com/bfwg/node-tinycrawler.
It is a javascript web crawler written under 1000 lines of code.
This should put you on the right track.
You can make a web crawler driven from a remote json file that opens all links from a page in new tabs as soon as each tab loads except ones that have already been opened. If you set up a with a browser extension running in a basic browser (nothing runs except the web browser and an internet config program) and had it shipped and installed somewhere with good internet, you could make a database of webpages with an old computer. That would just need to retrieve the content of each tab. You could do that for about $2000, contrary to most estimates for search engine costs. You'd just need to basically make your algorithm provide pages based on how much a term appears in the innerText property of the page, keywords, and description. You could also set up another PC to recrawl old pages from the one-time database and add more. I'd estimate it would take about 3 months and $20000, maximum.
Axios + Cheerio
You can do this with axios and cheerios. Check axios docs for response format.
const cheerio = require('cheerio');
const axios = require('axios');
//crawl
//get url
var url = 'http://amazon.com';
axios.get(url)
.then((res) => {
//response format
var body = res.data;
var statusCode = res.status;
var statusText = res.statusText;
var headers = res.headers;
var request = res.request;
var config = res.config;
//jquery
let $ = cheerio.load(body);
//example
//meta tags
var title = $('meta[name=title]').attr('content');
if(title == undefined || title == 'undefined'){
title = $('title').text();
}else{
title = title;
}
var description = $('meta[name=description]').attr('content');
var keywords = $('meta[name=keywords]').attr('content');
var author = $('meta[name=author]').attr('content');
var type = $('meta[http-equiv=content-type]').attr('content');
var favicon = $('link[rel="shortcut icon"]').attr('href');
}).catch(function (e) {
console.log(e);
});
Node-Fetch + Cheerio
You can do the same thing with node-fetch and cheerio.
fetch(url, {
method: "GET",
}).then(function(response){
//response
var html = response.text();
//return
return html;
})
.then(function(res) {
//response html
var html = res;
//jquery
let $ = cheerio.load(html);
//meta tags
var title = $('meta[name=title]').attr('content');
if(title == undefined || title == 'undefined'){
title = $('title').text();
}else{
title = title;
}
var description = $('meta[name=description]').attr('content');
var keywords = $('meta[name=keywords]').attr('content');
var author = $('meta[name=author]').attr('content');
var type = $('meta[http-equiv=content-type]').attr('content');
var favicon = $('link[rel="shortcut icon"]').attr('href');
})
.catch((error) => {
console.error('Error:', error);
});
am doing a project it requires a web site.on this site i have to darw state diagram for hyperlinks.that is how the hyperlinks are attached to one another on a site.am using html.how to get hyperlink id in another html file.i know about document.getElementById.
Thanks inadvance
That would require a way to access another HTML file through AJAX, which is not possible if it isn't on your domain or if CORS isn't enabled.
There's however quite a few things you could do:
Use your own server-side as proxy for fetching the HTML file.
Do the processing on the server-side and let JavaScript plot the data.
Do everything on the server-side.
If you'd like to get the ID's of a link you should use a HTML parser. Modern browsers include a such, it's called DOMParser. You'd do something like this:
var parser = new DOMParser();
var doc = parser.parseFromString(yourHTMLSource, 'text/html');
var links = doc.getElementsByTagName('a');
for(var i = 0, length = links.length; i < length; i++) {
links[i].getAttribute('id'); // -> Returns the ID of the link, if any
}
As I remember it, IE doesn't support this, but has it's own module for HTML parsing with some different methods, but still relatively easy to use.