Fs.writeFile in a for loop - write files one by one on each iteration of the loop?

Question

JavaScript

Hello, I'm trying to implement writing files one by one at each iteration of the loop, but the files are written all at once at the first iteration, while the code in the loop continues to be processed correctly. How to solve this problem?

var iterations = n;	
for (var i = 0; i < iterations; i++) {
    jsonData = JSON.stringify(obj[i], null, 2); 
    fs.writeFile("data"+i+".txt", jsonData, function(err) { if (err) { console.log(err);} });
                // More code
}

Answer 1

files are written all at once on the first iteration

Which is not surprising since fs.writeFile is an asynchronous function. Use a synchronous one, or you can write a wrapper that returns a Promise, or you can do it yourself:

const writeFile = (name, data) => new Promise((resolve, reject) => {
  fs.writeFile(name, data, function(err) {
    if (err) {
      reject(err);
    } else {
      resolve();
    }
  });
});

Either using util.promisify :
And use it with await:

for (let i = 0; i < iterations; i++) {
  await writeFile(`data${i}.txt`, JSON.stringify(obj[i], null, 2));
}

Answer 2

writeFileSync