Node.js fs.truncate() Method
Last Updated :
12 Oct, 2021
Improve
The fs.truncate() method in node.js is used to change the size of the file i.e either increase or decrease the file size. This method changes the length of the file at the path by len bytes. If len represents a length shorter than the file's current length, the file is truncated to that length. If it is greater than the file length is padded by appending null bytes (x00) until len is reached.
Syntax:
javascript
Output:
javascript
Output:
fs.truncate( path, len, callback )Parameters: This method accept three parameters as mentioned above and described below:
- path: It holds the path of targeted file. It can be either string, buffer or a url.
- len: It holds the length of the file after which the file will be truncated. It takes an integer input and it is not the mandatory condition as it is default set to 0.
- callback: The callback receives one argument, any exception throws in the call.
// Node.js program to demonstrate the
// fs.truncate() method
// Include the fs module
var fs = require('fs');
// Completely delete the content
// of the targeted file
fs.truncate('/path/to/file', 0, function() {
console.log('File Content Deleted')
});
File Content DeletedExample 2:
// Node.js program to demonstrate the
// fs.truncate() method
// Include the fs module
var fs = require('fs');
console.log("Content of file");
// Opening file
fs.open('input.txt', 'r+', function(err, fd) {
if (err) {
return console.error(err);
}
// Reading file
fs.read(fd, buf, 0, buf.length, 0, function(err, bytes){
if (err){
console.log(err);
}
// Truncating the file
fs.truncate('/path/to/file', 15, function(err, bytes){
if (err){
console.log(err);
}
// Content after truncating
console.log("New content of file");
fs.read(fd, buf, 0, buf.length, 0, function(err, bytes){
if (err) {
console.log(err);
}
// Print only read bytes to avoid junk.
if(bytes > 0) {
console.log(buf.slice(0, bytes).toString());
}
// Close the opened file.
fs.close(fd, function(err) {
if (err) {
console.log(err);
}
});
});
});
});
});
Content of file GeeksforGeeks example for truncate in node New content of file GeeksforGeeksReference: https://nodejs.org/api/fs.html#fs_fs_ftruncate_fd_len_callback
