How not to repeat information in a js Node file

Question

You guys, I got this comic:

const fs = require('fs');                                     
const produto = {
 nome: 'Smartphone',
 preco: 1749.99,                                               
 descontoo: 0.15
}                                                             
fs.appendFile('mynewfile2.txt', 
 JSON.stringify(produto), err => {                                                            
  console.log(err || 'Arquivo salvo');
});

Note that every time I run the comic it will repeat the information, but I want you not to repeat the same information, but I want to achieve this result in a simple way without changing much in the comic if possible. It is that I was answering a person here in stack overflow and I gave this answer and a comment made me see this problem, but I use the appendFile and I wonder if there’s any way to do that without needing to almost rewrite the entire comic

Answer 1

One way to solve the problem is to not use the appendFile.

Using your code, simply modify the appendFile for the function writeFile

Follow an example:

const fs = require('fs');
let data = null
try {
    data = JSON.parse(fs.readFileSync('./mynewfile2.txt'))
} catch (e) {
    console.log('não foi possível ler o arquivo.')
}

const produto = {
 nome: 'Smartphone',
 preco: 1749.99,
 descontoo: 0.15
}
const produtos = data || []
produtos.push(produto)
fs.writeFile('mynewfile2.txt', JSON.stringify(produtos), err => {
  console.log(err || 'Arquivo salvo');
});

Note that in the code I just changed the name of the function used in the module fs. Follows the documentation

When using the function appendFile you are always writing data at the end of the file. By using writeFile we are writing over the previously recorded information.

In this code we are using the try catch only to ensure the execution of the code successfully when the file does not exist.

Using this logic note that each time we run the code we are adding a new entity to the product array.