Question 1

How to make Floki parse HTML faster?

Accepted Answer

Switch to the fast_html backend by adding it to your dependencies and configuring it in config.exs, but note it requires C compiler and build tools. Benchmarks show it can be up to 20 times faster for large documents.

Question 2

What CSS selectors does Floki support compared to modern browsers?

Accepted Answer

Floki supports most standard CSS selectors like nth-child and attribute selectors, but has limitations such as :has and :not only for simple selectors. Check the README's selector table for specifics, as it doesn't support all pseudo-elements or complex combinators.

Question 3

Floki vs Elixir's built-in XML parsing for HTML?

Accepted Answer

Floki is specialized for HTML with CSS selector queries, making it better for web scraping, while Elixir's XML modules (like Xerces) are for XML and lack CSS support. Floki's API is more ergonomic for HTML manipulation in Elixir apps.

Question 4

How to extract all links from a webpage with Floki?

Accepted Answer

Parse the HTML with Floki.parse_document, then use Floki.find(document, "a") to get anchor elements, and Floki.attribute(anchors, "href") to extract the URLs. This is straightforward with the provided functions.

Question 5

Does Floki handle invalid HTML well?

Accepted Answer

It depends on the parser backend; the default mochiweb_html is lenient but may produce incorrect trees, while html5ever and fast_html are more spec-compliant. Always validate output for critical applications.

Question 6

How to suppress Floki's log messages in production?

Accepted Answer

Configure the :logger with :compile_time_purge_matching to filter debug and info messages, as mentioned in the README. This adds an extra step to avoid log noise in your application.

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