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Selector CSS untuk Presisi

Terapkan selector CSS untuk menemukan dan mengekstrak data dari elemen berdasarkan gaya dan atributnya.

Selector CSS untuk Presisi adalah pelajaran Web Scraping & Bots gratis di CoddyKit. Ini adalah pelajaran 2 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Web Scraping & Bots, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Web Scraping & Bots mencakup 4 pelajaran total.

Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.

What are CSS Selectors?

CSS selectors are patterns used to select elements on a web page. Think of them as precise instructions for finding specific pieces of information.

Web browsers use them to apply styles (CSS), and we'll use them to extract data efficiently.

Selectors for Data Extraction

In web scraping, CSS selectors provide a powerful way to pinpoint exactly the data you need from complex HTML.

  • They are often more concise than XPath.
  • Many developers are already familiar with CSS.
  • BeautifulSoup has excellent support for them.

Selecting by Tag Name

The simplest selector is the tag name. This selects all elements of that type.

For example, p selects all paragraph tags, and a selects all anchor (link) tags.

Example: To find all list items, you'd use li.

from bs4 import BeautifulSoup

html_doc = """
<html><body>
  <h1>My Title</h1>
  <p>First paragraph.</p>
  <ul>
    <li>Item 1</li>
    <li>Item 2</li>
  </ul>
</body></html>
"""
soup = BeautifulSoup(html_doc, 'html.parser')

# Select all 'p' tags
paragraphs = soup.select('p')
for p in paragraphs:
    print(p.get_text())

Class and ID Selectors

You can select elements based on their class or ID attributes. These are very common for styling and unique identification.

  • Class: Use a dot . before the class name (e.g., .product-title).
  • ID: Use a hash # before the ID name (e.g., #main-content). IDs should be unique!
from bs4 import BeautifulSoup

html_doc = """
<div id="header">Welcome</div>
<p class="intro">Hello there!</p>
<p class="intro">Another intro.</p>
"""
soup = BeautifulSoup(html_doc, 'html.parser')

header = soup.select_one('#header')
print("Header:", header.get_text())

intros = soup.select('.intro')
for p in intros:
    print("Intro:", p.get_text())

Selecting Nested Elements

To select elements that are inside other elements, you use a space between selectors. This is called a descendant selector.

It means "find an element (B) that is anywhere inside another element (A)".

Example: div p selects all <p> tags that are inside any <div> tag.

from bs4 import BeautifulSoup

html_doc = """
<div>
  <p>Inside div paragraph 1</p>
  <span>
    <p>Inside span inside div</p>
  </span>
</div>
<p>Outside div paragraph</p>
"""
soup = BeautifulSoup(html_doc, 'html.parser')

div_paragraphs = soup.select('div p')
for p in div_paragraphs:
    print(p.get_text())

Direct Children Only

Sometimes you only want elements that are direct children of another element, not just any descendant.

Use the greater than symbol > for this.

Example: ul > li selects all <li> tags that are direct children of a <ul> tag.

from bs4 import BeautifulSoup

html_doc = """
<div class="container">
  <p>Direct child P</p>
  <div>
    <p>Nested P (not direct)</p>
  </div>
</div>
"""
soup = BeautifulSoup(html_doc, 'html.parser')

direct_p = soup.select('.container > p')
for p in direct_p:
    print(p.get_text())

Selecting by Attributes

You can select elements based on their attributes and even their attribute values!

  • [attr]: Has the attribute (e.g., [href]).
  • [attr="value"]: Has attribute with exact value (e.g., [target="_blank"]).
  • [attr^="value"]: Attribute value starts with (e.g., [src^="data:"]).
  • [attr$="value"]: Attribute value ends with (e.g., [alt$="logo"]).
  • [attr*="value"]: Attribute value contains (e.g., [id*="item"]).
from bs4 import BeautifulSoup

html_doc = """
<a href="/about">About Us</a>
<a href="https://example.com/contact" target="_blank">Contact</a>
<img src="image.jpg" alt="product image">
"""
soup = BeautifulSoup(html_doc, 'html.parser')

# Select links with target="_blank"
external_links = soup.select('a[target="_blank"]')
for link in external_links:
    print("External:", link.get('href'))

# Select images with alt containing "image"
product_images = soup.select('img[alt*="image"]')
for img in product_images:
    print("Image:", img.get('src'))

Combining with Commas

To select elements that match any of several different selectors, you can separate them with a comma ,.

This is useful when you want to gather data from different types of elements or locations.

Example: h1, h2, h3 selects all heading tags of level 1, 2, or 3.

from bs4 import BeautifulSoup

html_doc = """
<h1>Main Heading</h1>
<p>Some text.</p>
<h2>Sub Heading</h2>
<div>Another div.</div>
"""
soup = BeautifulSoup(html_doc, 'html.parser')

headings = soup.select('h1, h2')
for h in headings:
    print(h.get_text())

Pseudo-classes for Position

CSS pseudo-classes allow selection based on state or position, not just attributes. For scraping, position-based ones are very useful.

  • :first-child: Selects the first child element.
  • :last-child: Selects the last child element.
  • :nth-of-type(n): Selects the Nth element of a specific type (e.g., li:nth-of-type(2) for the second list item).
from bs4 import BeautifulSoup

html_doc = """
<ul>
  <li>First item</li>
  <li>Second item</li>
  <li>Third item</li>
</ul>
"""
soup = BeautifulSoup(html_doc, 'html.parser')

first_item = soup.select_one('li:first-child')
print("First:", first_item.get_text())

second_item = soup.select_one('li:nth-of-type(2)')
print("Second:", second_item.get_text())

Practical CSS Selector Use

Let's combine what we've learned to extract specific data from a sample product listing.

We want the title and price of the first product.

from bs4 import BeautifulSoup

html_doc = """
<div class="product-list">
  <div class="product-card">
    <h3 class="product-title">Laptop X1</h3>
    <p class="product-price">$999.99</p>
    <button class="add-to-cart">Add</button>
  </div>
  <div class="product-card">
    <h3 class="product-title">Mouse Z2</h3>
    <p class="product-price">$29.99</p>
    <button class="add-to-cart">Add</button>
  </div>
</div>
"""
soup = BeautifulSoup(html_doc, 'html.parser')

# Select the first product card
first_product = soup.select_one('.product-card:first-of-type')

if first_product:
    title = first_product.select_one('.product-title')
    price = first_product.select_one('.product-price')
    print("Title:", title.get_text())
    print("Price:", price.get_text())
else:
    print("No product found.")

Quick Check on Selectors

Given the HTML below, what CSS selector would correctly select the text "Product Name 2"?

<div class="items">
  <div id="item-1">
    <span class="name">Product Name 1</span>
  </div>
  <div id="item-2">
    <span class="name">Product Name 2</span>
  </div>
  <p class="name">Other Name</p>
</div>

Recap: CSS Selectors

Great job! You've mastered the basics of CSS selectors for web scraping.

  • We learned to select by tag, class, and ID.
  • We explored descendant (space) and direct child (>) selectors.
  • You can filter by attributes ([attr="value"]) and use pseudo-classes like :first-child.
  • BeautifulSoup's .select() and .select_one() methods make using them easy in Python.

Next, we'll look into XPath for even more powerful selections!

Pertanyaan yang Sering Diajukan

Apakah pelajaran “Selector CSS untuk Presisi” gratis?

Ya — teks lengkap “Selector CSS untuk Presisi” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Web Scraping & Bots, upgrade ke CoddyKit PRO. Kursus Web Scraping & Bots mencakup 4 pelajaran total.

Apa yang akan aku pelajari di “Selector CSS untuk Presisi”?

Terapkan selector CSS untuk menemukan dan mengekstrak data dari elemen berdasarkan gaya dan atributnya. Kamu berlatih Web Scraping & Bots dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.

Apakah aku perlu pengalaman untuk memulai Web Scraping & Bots?

Tidak diperlukan pengalaman sebelumnya. Web Scraping & Bots di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 2 dari 4.

Berapa lama pelajaran “Selector CSS untuk Presisi” memakan waktu?

Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.

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Semua pelajaran dalam kursus ini

  1. Menavigasi Struktur HTML yang Kompleks
  2. Selector CSS untuk Presisi
  3. XPath untuk Seleksi Andal
  4. Mengekstrak Data dari Tabel HTML
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