merge-json.js

const fs = require('fs');
const path = require('path');

//List all your folders you want to merge
// This will create One single merged JSON file named merged.json inside each folder.
// NOTE: this requires all the file must be having Array. incase not you can handle the cases in line 13 Here.
const folders = [
    '/Users/saikatharryc/Documents/testing'
]
const init = (dirz)=> {
  return fs.readdirSync(dirz)
           .filter(name => path.extname(name) === '.json')
           .map(name =>require(path.join(dirz, name)));
}
const main = ()=>{
folders.forEach(f=>{
arrays = init(f)
// console.log(arrays[0])
var merged = [].concat.apply([], arrays);
fs.writeFileSync(path.join(f,'merged.json' ),JSON.stringify(merged, null, 4));
console.log(f+' : '+merged.length)
})
}

main()