Sort object keys in JSON file

sortJson.js

#!/usr/bin/env node

/////// SORT OBJECT KEYS OF JSON FILE ////////////////////////////////////////////////////////////////
// TODO make recursive for object with depth > 1
/////////////////////////////////////////////////////////////////////////

const fs = require("fs")

const options = "utf8"
const file = process.argv[2]
if(!file) throw new Error("requires json file as argument")

let json = fs.readFileSync(file, options)
json = JSON.parse(json)
let keys = Object.keys(json).sort()
let ret = {}
keys.forEach(function (key) {
    ret[key] = json[key]
})

let output = JSON.stringify(ret, null, "   ")
// this will overwrite the source file TODO make optional
fs.writeFileSync(file, output, {encoding: options})
console.log(output)