Modify all json files in a folder

example.js

const {executeCommandLineCmd, getFile, writeFile} = require('hoopoe');
// imagine you have a number of json files in a folder called showcase/data/
executeCommandLineCmd('ls -a showcase/data').then(({stdout}) => {
  // Build a list of desired file names   
  const fileNames = stdout.split('\n').filter(name => name.includes('.json'));

  // Execute your actions over each of them  
  fileNames.forEach(fileName => {
    // get the file    
    getFile(`./showcase/data/${fileName}`)
      // parse it       
      .then(d => JSON.parse(d))
      .then(d => {
        // make your modifications        
        d.EXAMPLE_PROPERTY = 'WOWZA!';
        // write the file back to where it was
        writeFile(`./showcase/data/${fileName}`, JSON.stringify(d, null, 2));
      });
  });
});

// CAVEAT: this executes everything simulatenously, 
// if you want do it in series then you can make use of hoopoe's executePromisesInSeries