How can I append more text to a text file in Node.js?
Dung Do Tien
Jul 02 2021
250
Hi, I'm a newbie in Nodejs.
I created a small project to get data from a database and put it into a txt file and content is separate by a comma(,) I try as below:
const fs = require('fs');
fs.writeFile('product_ids.txt', '123,232,4334,323', function (err) {
if (err) throw err;
console.log('It\'s saved!');
}); // => product_ids.txt erased, contains only '123,232,4334,323'
When I run code, the product_ids only content latest ids, and all data before are clear. How can I keep all of them?
Thanks for any suggestions!
Have 2 answer(s) found.
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M0
Milan cubes Jul 02 2021
Your way only use when want to create and add content into a file. If you want to append more text into a file you can do as below:
Synchronously::
const fs = require('fs'); fs.appendFile('message.txt', 'data to append', function (err) { if (err) throw err; console.log('Saved!'); });Asynchronously
const fs = require('fs'); fs.appendFileSync('message.txt', 'data to append');I hope it useful for you!!
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G0
Gornpol Suksumrate Jul 02 2021
Your code using
createWriteStream()method to creates a file descriptor for every writeslogStream.end()method is better because it asks the node to close immediately after the write.var fs = require('fs'); var logStream = fs.createWriteStream('log.txt', {flags: 'a'}); // use {flags: 'a'} to append and {flags: 'w'} to erase and write a new file logStream.write('Initial line...'); logStream.end('this is the end line');And it works for me.
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