StyleSheetList

The StyleSheetList interface represents a list of StyleSheet.

It is an array-like object but can't be iterated over using Array methods. However It can be iterated over in a standard for loop over its indices, or converted to an Array.

for (let i = 0; i < document.styleSheets.length; i++) {
  let styleSheet = document.styleSheets[i];
}

const allCSS = [...document.styleSheets]
  .map(styleSheet => {
    try {
      return [...styleSheet.cssRules]
        .map(rule => rule.cssText)
        .join('');
    } catch (e) {
      console.log('Access to stylesheet %s is denied. Ignoring...', styleSheet.href);
    }
  })
  .filter(Boolean)
  .join('\n');