Node.js file stats

Every file comes with a set of details that we can inspect using Node.js. In particular, using the stat() method provided by the fs module.

You call it passing a file path, and once Node.js gets the file details it will call the callback function you pass, with 2 parameters: an error message, and the file stats:

const fs = require('node:fs');

fs.stat('/Users/joe/test.txt', (err, stats) => {
  if (err) {
    console.error(err);
  }
  // we have access to the file stats in `stats`
});

Node.js also provides a sync method, which blocks the thread until the file stats are ready:

const fs = require('node:fs');

try {
  const stats = fs.statSync('/Users/joe/test.txt');
} catch (err) {
  console.error(err);
}

The file information is included in the stats variable. What kind of information can we extract using the stats?

A lot, including:

• if the file is a directory or a file, using stats.isFile() and stats.isDirectory()
• if the file is a symbolic link using stats.isSymbolicLink()
• the file size in bytes using stats.size.

There are other advanced methods, but the bulk of what you'll use in your day-to-day programming is this.

const fs = require('node:fs');

fs.stat('/Users/joe/test.txt', (err, stats) => {
  if (err) {
    console.error(err);
    return;
  }

  stats.isFile(); // true
  stats.isDirectory(); // false
  stats.isSymbolicLink(); // false
  console.log(stats.size); // 1024000 //= 1MB
});

You can also use promise-based fsPromises.stat() method offered by the fs/promises module if you like:

const fs = require('node:fs/promises');

async function example() {
  try {
    const stats = await fs.stat('/Users/joe/test.txt');
    stats.isFile(); // true
    stats.isDirectory(); // false
    stats.isSymbolicLink(); // false
    console.log(stats.size); // 1024000 //= 1MB
  } catch (err) {
    console.log(err);
  }
}
example();

You can read more about the fs module in the official documentation.