Cheerio Parsing

npm install cheerio axios

const cheerio = require('cheerio');
const axios = require('axios');

// Load from string
const $ = cheerio.load('<html><body><h1>Hello</h1></body></html>');

// Load with options
const $ = cheerio.load(html, {
  xmlMode: false,           // Parse as XML
  decodeEntities: true,     // Decode HTML entities
  lowerCaseTags: false,     // Keep tag case
  lowerCaseAttributeNames: false
});

// Fetch and parse
async function fetchAndParse(url) {
  const response = await axios.get(url);
  return cheerio.load(response.data);
}

// By tag
$('h1')

// By class
$('.article')

// By ID
$('#main-content')

// By attribute
$('[data-id="123"]')
$('a[href^="https://"]')  // Starts with
$('a[href$=".pdf"]')      // Ends with
$('a[href*="example"]')   // Contains

// Combinations
$('div.article > h2')     // Direct child
$('div.article h2')       // Any descendant
$('h2 + p')               // Adjacent sibling
$('h2 ~ p')               // General sibling

// Pseudo-selectors
$('li:first-child')
$('li:last-child')
$('li:nth-child(2)')
$('li:nth-child(odd)')
$('tr:even')
$('input:not([type="hidden"])')
$('p:contains("specific text")')

// Select multiple types
$('h1, h2, h3')

// Chain selections
$('.article').find('.title')

// Get text (includes child text)
const text = $('h1').text();

// Get trimmed text
const text = $('h1').text().trim();

// Get HTML
const html = $('div.content').html();

// Get outer HTML
const outerHtml = $.html($('div.content'));

// Get attribute
const href = $('a').attr('href');
const src = $('img').attr('src');

// Get data attributes
const id = $('div').data('id');  // data-id attribute

// Check if attribute exists
const hasClass = $('div').hasClass('active');

// Iterate with each
const items = [];
$('.product').each((index, element) => {
  items.push({
    name: $(element).find('.name').text().trim(),
    price: $(element).find('.price').text().trim(),
    url: $(element).find('a').attr('href')
  });
});

// Map to array
const titles = $('h2').map((i, el) => $(el).text()).get();

// Filter elements
const featured = $('.product').filter('.featured');

// First/Last
const first = $('li').first();
const last = $('li').last();

// Get by index
const third = $('li').eq(2);

// Parent
$('span').parent()
$('span').parents()          // All ancestors
$('span').parents('.container')  // Specific ancestor
$('span').closest('.wrapper')    // Nearest ancestor matching selector

// Children
$('ul').children()           // Direct children
$('ul').children('li.active') // Filtered children
$('div').contents()          // Including text nodes

// Siblings
$('li').siblings()
$('li').next()
$('li').nextAll()
$('li').prev()
$('li').prevAll()

// Filter by selector
$('li').filter('.active')

// Filter by function
$('li').filter((i, el) => $(el).data('price') > 100)

// Find within selection
$('.article').find('img')

// Check conditions
$('li').is('.active')  // Returns boolean
$('li').has('span')    // Has descendant matching selector

function extractTable(tableSelector) {
  const $ = this;
  const headers = [];
  const rows = [];

  // Get headers
  $(tableSelector).find('th').each((i, el) => {
    headers.push($(el).text().trim());
  });

  // Get rows
  $(tableSelector).find('tbody tr').each((i, row) => {
    const rowData = {};
    $(row).find('td').each((j, cell) => {
      rowData[headers[j]] = $(cell).text().trim();
    });
    rows.push(rowData);
  });

  return rows;
}

function extractList(selector, itemExtractor) {
  return $(selector).map((i, el) => itemExtractor($(el))).get();
}

// Usage
const products = extractList('.product', ($el) => ({
  name: $el.find('.name').text().trim(),
  price: parseFloat($el.find('.price').text().replace('$', '')),
  image: $el.find('img').attr('src'),
  link: $el.find('a').attr('href')
}));

function extractPaginationLinks() {
  return $('.pagination a')
    .map((i, el) => $(el).attr('href'))
    .get()
    .filter(href => href && !href.includes('#'));
}

// Safe extraction with defaults
function safeText(selector, defaultValue = '') {
  const el = $(selector);
  return el.length ? el.text().trim() : defaultValue;
}

function safeAttr(selector, attr, defaultValue = null) {
  const el = $(selector);
  return el.length ? el.attr(attr) : defaultValue;
}

// Optional chaining pattern
const price = $('.price').first().text()?.trim() || 'N/A';

const { URL } = require('url');

function resolveUrl(baseUrl, relativeUrl) {
  if (!relativeUrl) return null;
  try {
    return new URL(relativeUrl, baseUrl).href;
  } catch {
    return relativeUrl;
  }
}

// Usage
const baseUrl = 'https://example.com/products/';
$('a').each((i, el) => {
  const href = $(el).attr('href');
  const absoluteUrl = resolveUrl(baseUrl, href);
  console.log(absoluteUrl);
});

// Cache selections
const $products = $('.product');
$products.each((i, el) => {
  const $product = $(el);  // Wrap once
  // Use $product multiple times
});

// Limit parsing scope
const $article = $('.article');
const title = $article.find('.title').text();  // Searches only within article

// Use specific selectors
// Good
$('div.product > h2.title')
// Less efficient
$('div').find('.product').find('h2').filter('.title')

const cheerio = require('cheerio');
const axios = require('axios');

async function scrapeProducts(url) {
  const response = await axios.get(url, {
    headers: {
      'User-Agent': 'Mozilla/5.0 (compatible; MyScraper/1.0)'
    }
  });

  const $ = cheerio.load(response.data);
  const products = [];

  $('.product-card').each((index, element) => {
    const $el = $(element);

    products.push({
      name: $el.find('.product-title').text().trim(),
      price: parseFloat(
        $el.find('.price').text().replace(/[^0-9.]/g, '')
      ),
      rating: parseFloat($el.find('.rating').attr('data-rating')) || null,
      image: $el.find('img').attr('src'),
      url: new URL($el.find('a').attr('href'), url).href,
      inStock: !$el.find('.out-of-stock').length
    });
  });

  return products;
}

// With error handling
async function safeScrape(url) {
  try {
    return await scrapeProducts(url);
  } catch (error) {
    console.error(`Failed to scrape ${url}:`, error.message);
    return [];
  }
}