CSS Button Generator
About CSS Selector Tester
The Real-Time CSS Selector Tester & Query Selector Sandbox evaluates complex CSS selectors against live HTML markup, highlighting matching DOM elements in real time with match counts, querySelector performance metrics, and DOM tree node inspection.
How to Use CSS Selector Tester
Step 1
Paste your HTML markup into the HTML pane.
Step 2
Type your CSS selector into the query bar.
Step 3
Inspect matching elements highlighted with glowing bounding boxes in real time.
Step 4
Review match count and element details.
Practical Use Cases for CSS Selector Tester
Testing Complex CSS & XPath Selectors
Verify advanced combinators (child `>`, sibling `+`, general sibling `~`) and pseudo-classes (`:nth-child`, `:has`, `:is`) against real HTML.
Web Scraping & DOM Scraping Prototyping
Test CSS selectors before writing Puppeteer, Playwright, or Cheerio web scraping scripts to ensure robust element targeting.
Input & Output Examples
Testing Child Selector Match
Selector: "ul.menu > li:not(.disabled)", HTML: 5-item list with 1 disabled item
4 Elements Matched (80% match rate) | Highlighted in visual DOM tree preview
Key Features & Performance
- ✓Evaluates CSS selectors against custom HTML markup using browser native `querySelectorAll`.
- ✓Highlights matching elements in a live interactive visual preview and syntax tree.
- ✓Displays total matches count and execution speed in milliseconds.
- ✓Detects syntax errors in invalid CSS selector strings.
- ✓100% Client-Side memory execution.
- ✓1-Click Copy matched elements.
Key Terminology & Definitions
`document.querySelectorAll()`
The standard browser DOM API that returns a static NodeList of all document elements matching a specified CSS selector string.
CSS Combinators
Characters defining relationships between selectors: descendant (space), child (`>`), adjacent sibling (`+`), and general sibling (`~`).