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Development

Check if cookies are enabled

function areCookiesEnabled() 
	{
		var cookieEnabled = (navigator.cookieEnabled) ? true : false;
		if (typeof navigator.cookieEnabled == "undefined" && !cookieEnabled)
		{
			document.cookie = "test";
			cookieEnabled = (document.cookie.indexOf("test") != -1) ? true : false;
		}
		return cookieEnabled;
	}

Navigator is the interface represents the state and the identity of the user agent. It allows scripts to query it and to register themselves to carry on some activities.
Navigator object can be retrieved using the read-only window.navigator property.

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Development

Check if sessionStorage is enabled

function isStorageEnabled() {
	try{
		sessionStorage.setItem("test","value");
		if(sessionStorage.getItem("test") == "value") {
			sessionStorage.removeItem("test");
			return true;
		} else {
			return false;
		}
	} catch(err) {
		return false;
	}
}
Categories
Development

VPS/VDS firewall settings to let Node.js be accessible externally

Problem

I’ve made a simple node.js server at VDS:

var http = require('http');
http.createServer(function (req, res) {
  let port = 9999; 
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(post, '0.0.0.0');
console.log('Server running at port ' + port);

It works outputting:

Server running at port 9999

yet I can’t reach it at VPS/VDS IP where the code is residing: http://webscraping.pro:9999/ How to solve that?

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Development

Fast scrape of a simple website using Node.js, Apify & Cheerio scraper

We recently composed a scraper that works to extract data of a static site. By a static site, we mean such a site that does not utilize JS scripting that loads or transforms on-site data.

If you are interested in a scrape JS-rendered site, please read the following: Scraping a Javascript-dependent website with puppeteer.

Technologies stack

  1. Node.js, the server-side JS environment. The main characteristic of Node.js is the code asynchronous execution.
  2. Apify SDK, the scalable web scraping and crawling library for JavaScript/Node.js. Let’s highlight its excellent characteristics:
  • automatically scales a pool of headless Chrome/Puppeteer instances
  • maintains queues of URLs to crawl (handled, pending) – this makes it possible to accommodate crawler possible failures and resumes.
  • saves crawl results to a convenient [json] dataset (local or in the cloud)
  • allows proxies rotation

    We’ll use a Cheerio crawler of Apify to crawl and extract data off the target site. The target is https://www.ebinger-gmbh.com/.
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Development

Node.js, Apify, how to fill in RequestQueue from txt file

When working with Apify crawlers, it’s necessary to init RequestQueue. How to fill in RequestQueue from txt file?

Given

A text file with urls to crawl. In our case it’s categories.txt. We’ll use LineReader node package to open and iterate the file line by line.
LineReader to install:

npm i --save line-reader  

Since requestQueue methods return Promise, when iterating over the lines of the file we need to apply async function for each line to be added as url into the requestQueue.

The code

const queue_name ='ebinger';
const base_url = 'https://www.ebinger.com/';

Apify.main(async () => {
 
	const requestQueue = await Apify.openRequestQueue(queue_name);
	const lineReader = require('line-reader');
	lineReader.eachLine('categories.txt', async function(line) {
		//console.log('adding ', line);
		let url = base_url + line.trim(); 
		await requestQueue.addRequest({ url: url });
	}); 
	var { totalRequestCount, handledRequestCount, pendingRequestCount, name } = await requestQueue.getInfo();
	console.log(`RequestQueue "${name}" with requests:` );
	console.log(' handledRequestCount:', handledRequestCount);
	console.log(' pendingRequestCount:', pendingRequestCount);
	console.log(' totalRequestCount:'  , totalRequestCount);
...
Categories
Development

How to extract emails, phones, links (urls) from text fragments?

Recently I noticed the question about extracting emails, phones, links(urls) from text fragments and immediately I decided to write this short post.

Regex comes to rescue

Each of the following: email, phones, link, form a category that falls under/matches a certain text pattern. What are the text patterns ? These are regexes, aka regex patterns, short for regular expressions. Eg. most emails fit into the following regex pattern: 

^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$

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Development

Composer failed to download guzzle package

I’ve met with the challenge that composer failed to load guzzle library file:

https://packagist.org/p/guzzlehttp/guzzle%241f150aaa79afd8bc5d6f08f730634a0d60
f5dfcd1dd4a6fc5263fb4b1cefeb16.json" 
file could not be downloaded (HTTP/1.1 404 Not Found)

The solution has been the following:

composer clear-cache
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Development Guest posting Web Scraping Software

Octoparse Alternatives

Let me tell you what you already know! Octoparse is a great web scraping tool! But like every great tool, it’s got its limitations. At times, you may wonder if there are any alternatives to Octoparse. We wondered the same and put together this blog to provide you a short list of Octoparse alternatives along with their features and distinguishing factors. Let’s get started!

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Development

Selenium Web Scraping in simple words

Question: What is Selenium web scraping?

Answer: A picture is better than 1000 words:selenium main diagram

So, you make a program with Python, PHP, JAVA, Ruby and whatever language you use in order to browse(), select(), click(), submit(), save(), etc.,  target web pages.

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Development

Linkedin scrape guide lines

The LinkedIn crawl success rate is low; one request that a bot makes might require several retries to be successful. So, here we share the crucial Linkedin scraping guide lines.

  1. Rate limit
    Limit the crawling rate for LinkedIn. The acceptable approximate frequency is: 1 request every second, 60 requests per minute.
  2. Public pages only
    LinkedIn allows for bots only public pages; pages that are private cannot be crawled.