Critical CSS Generator

Extract critical css (above the fold) for a specific site using puppeteer.

Usage

1. npm i critical-css-generator
2. Run the following:

const critical = require('critical-css-generator');
critical.generate({
    url: 'https://www.vistaprint.com/business-cards',
    path: 'critical-business-cards.css',
    viewport: true
});

3. A critical-business-cards.css file will be generated. Add this into the page!

Options include:

• url: URL to get critical CSS for.
• path: Where to output critical CSS. Default is critical.css.
• deviceName: What device to run it on. Default is Pixel 2.
• waitFor: How long to wait (in ms) after page navigation before generating critical CSS. Some pages have long load times, so specifying this may be helpful. Default is 20000.
• viewport: Whether to generate critical CSS (only above the fold content) or generate used CSS for the whole page. Default is true.
• cssSelectorFilter: An array of CSS selectors (regex) to always include in the generated CSS. For example: [/mobile/]. Default is [].
• includeCssFiles: An array of CSS file names (regex) to always include in the generated CSS. Default is [].
• excludeCssFiles: An array of CSS file names (regex) to always exclude in the generated CSS. Default is [].
• generateSeparateFiles: Generate separate critical CSS files per each CSS file used. The files are stored in a critical/ directory. Default is false.