Question 1

How to minify CSS files with clean-css in a Node.js build?

Accepted Answer

Install via npm, require the module, and use the minify method with options like level or compatibility. For example, new CleanCSS({ level: 2 }).minify(source) returns optimized CSS and stats, as shown in the README examples for integration with tools like Gulp.

Question 2

clean-css vs cssnano: which is better for Webpack?

Accepted Answer

clean-css excels in fine-tuned, standalone minification with extensive configuration, while cssnano is often preferred for PostCSS-based workflows. Choose clean-css if you need granular control in Node.js pipelines, or cssnano for seamless PostCSS integration and plugin ecosystems.

Question 3

Does clean-css support CSS custom properties (variables)?

Accepted Answer

Yes, it optimizes CSS variables using the level 1 variableValueOptimizers option, which applies value optimizers like color or fraction transformations to variable values, as detailed in the version 5.3 update notes.

Question 4

How to handle remote @import rules with clean-css?

Accepted Answer

Set the inline option to include 'remote' and optionally provide a fetch function for custom request handling. Note that remote @imports are not inlined by default for security, and asynchronous minify with a callback is required for proper processing.

Question 5

What are common errors when using clean-css?

Accepted Answer

Errors include missing local @import resources or invalid CSS syntax, with warnings for issues like empty properties. The output object lists errors and warnings to help debug, such as 'Ignoring local @import' messages for missing files.

Question 6

Can clean-css beautify or format CSS output?

Accepted Answer

Yes, use the format option with settings like 'beautify' for readable output or fine-tune breaks and indentation. For instance, format: { breaks: { afterComment: true } } adds line breaks after comments, as described in the formatting options section.

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