Beginner&#s Guide to Web Scraping and Proxy Setup with JavaScript

Use JavaScript code to simulate user operations to obtain the required information. This includes simulating user operations such as opening web pages, clicking links, entering keywords, etc., and extracting the required information from the web pages.

The Core Principle of Javascript Web Scraping

Use JavaScript code to simulate user operations to obtain the required information. This includes simulating user operations such as opening web pages, clicking links, entering keywords, etc., and extracting the required information from the web pages.

Javascript Web Scraping Common Tools

You Can Choose to Use the Xmlhttprequest Object, ‌Fetch Api, ‌jQuery's Ajax Method, Etc. to Request and Capture Data‌. These Methods Allow You to Send Http Requests and Get Server Responses.

How Does Javascript Web Scraping Handle Cross-Domain Issues?

Due to the Browser's Homology Policy Restrictions, Javascript Cannot Directly Access Resources Under Other Domains. You Can Use Technologies Such as Jsonp and Cors to Implement Cross-Domain Requests, or Use Proxies, Set Browser Parameters, Etc. to Solve Cross-Domain Issues.

Setting Proxy Ip When Web Scraping Using Javascript

When Using Javascript for Web Scraping, Setting Up a Proxy Can Effectively Hide the Real Ip Address, Improve Security, or Bypass Some Access Restrictions. the Steps to Set Up a Proxy Ip Usually Include:

1. Get a proxy

First, you need to get an available proxy.
Proxies are usually provided by third-party service providers. You can find available proxies through search engines or related technical forums, and test them to ensure their availability.

2. Set up a proxy server

In JavaScript, you can specify proxy server information by setting system properties or using a specific HTTP library.
For example, when using the http or https module, you can create a new Agent object and set its proxy property.

3. Initiate a request

After setting up the proxy server, you can initiate a network request through the proxy to scrap the web page.

Example of Setting Up a Proxy When Scraping With Javascript

An Example of Setting a Proxy When Using Javascript for Web Scraping Is as Follows:

const http = require('http');
const https = require('https');

// Set IP address and port
const proxy = 'http://IP address:port';

http.globalAgent = new http.Agent({ proxy: proxy });
https.globalAgent = new https.Agent({ proxy: proxy });

// Use the http or https modules to make requests, they will automatically use the configured proxy
https.get('http://example.com', (res) => {
  let data = '';

  // Receive data fragment
  res.on('data', (chunk) => {
    data += chunk;
  });

  // Data received
  res.on('end', () => {
    console.log(data);
  });
}).on('error', (err) => {
  console.error('Error: ' + err.message);
});

‌Note‌:‌ You need to replace 'http://IP address:port' with the IP address and port number you actually obtained. ‌‌

How to store data locally using JavaScript?

There are several ways to store data locally using JavaScript:

• localStorage: long-term data storage. Unless manually deleted, data will be kept in the browser. You can use localStorage.setItem(key, value) to store data, localStorage.getItem(key) to read data, and localStorage.removeItem(key) to delete data.

• sessionStorage: session-level storage. Data disappears after the browser is closed. Its usage is similar to localStorage.

• Cookie: storage string. The size limit is about 4KB. The storage timeliness is set to session level by default. The expiration time can be

• set manually. The operation must rely on the server.

• IndexedDB: used to store large amounts of structured data, including files/blobs. The storage capacity is theoretically unlimited.
  Through the above steps, you can complete the process of JavaScript scraping web page data and storing it.

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