snippet1.js

// customer.json
{
    "name": "Mega Corp.",
    "order_count": 83,
    "address": "Infinity Loop Drive",
}

snippet2.js

const fs = require('fs')

fs.readFile('./customer.json', 'utf8', (err, jsonString) => {
    if (err) {
        console.log("File read failed:", err)
        return
    }
    console.log('File data:', jsonString) 
})

snippet3.js

const fs = require('fs')

fs.readFile('./customer.json', 'utf8', (err, jsonString) => {
    if (err) {
        console.log("Error reading file from disk:", err)
        return
    }
    try {
        const customer = JSON.parse(jsonString)
        console.log("Customer address is:", customer.address) 
                // => "Customer address is: Infinity Loop Drive"

    } catch(err) {
        console.log('Error parsing JSON string:', err)
    }
})

snippet4.js

try {
  const jsonString = fs.readFileSync('./customer.json')
  const customer = JSON.parse(jsonString)
} catch(err) {
  console.log(err)
  return
}

console.log(customer.address) // => "Infinity Loop Drive"

snippet5.js

const fs = require('fs')

function jsonReader(filePath, cb) {
    fs.readFile(filePath, (err, fileData) => {
        if (err) {
            return cb && cb(err)
        }
        try {
            const object = JSON.parse(fileData)
            return cb && cb(null, object)
        } catch(err) {
            return cb && cb(err)
        }
    })
}

jsonReader('./customer.json', (err, customer) => {
    if (err) {
        console.log(err)
        return
    }
    console.log(customer.address) // => "Infinity Loop Drive"
})

snippet6.js

const customer = {
    name: "Newbie Corp.",
    order_count: 0,
    address: "Po Box City",
}

const jsonString = JSON.stringify(customer)
console.log(jsonString) 
    // => "{"name":"Newbie Co.","address":"Po Box City","order_count":0}"

snippet7.js

const fs = require('fs')

const customer = {
    name: "Newbie Co.",
    order_count: 0,
    address: "Po Box City",
}

const jsonString = JSON.stringify(customer)

fs.writeFile('./newCustomer.json', jsonString, err => {
    if (err) {
        console.log('Error writing file', err)
    } else {
        console.log('Successfully wrote file')
    }
})

snippet8.js

const jsonString = JSON.stringify(customer)

fs.writeFileSync('./newCustomer.json', jsonString)

snippet9.js

jsonReader('./customer.json', (err, customer) => {
    if (err) {
        console.log('Error reading file:',err)
        return
    }

    // increase customer order count by 1
    customer.order_count += 1

    fs.writeFile('./customer.json', JSON.stringify(customer), (err) => {
        if (err) console.log('Error writing file:', err)
    })
})