'use strict'; let css = require('css'); let fs = require('fs'); let file = './primo-explore/lib/app-edb918fbd4.css'; let cssContent = fs.readFileSync(file, {encoding: 'utf8'}); let obj = css.parse(cssContent,{source: file}); let colorRules = []; for(let rule of obj.stylesheet.rules) { if(!rule.declarations) { continue; } let colorDeclarations = rule.declarations.filter(f => f.property && f.property.includes('color')); if(!colorDeclarations.length) { continue; } rule.declarations = colorDeclarations; colorRules.push(rule); } obj.stylesheet.rules = colorRules; console.log(css.stringify(obj));