const langs = require('./src/lib/languages'); const fs = require('fs'); var newLangs = {}; Object.keys(langs).map((l, index) => { // accept only prose and programming if (langs[l].type === 'programming' || langs[l].type === 'prose') { newLangs[l] = langs[l]; } }); fs.writeFileSync('new.js', JSON.stringify(newLangs));