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 import fsfs = require: anyrequire('node:fs');

import fsfs.stat('/Users/joe/test.txt', (err: anyerr, stats: anystats) => {
  if (err: anyerr) {
    var console: Consoleconsole.Console.error(...data: any[]): void[MDN Reference](https://developer.mozilla.org/docs/Web/API/console/error_static)error(err: anyerr);
  }
  // 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 import fsfs = require: anyrequire('node:fs');

try {
  const const stats: anystats = import fsfs.statSync('/Users/joe/test.txt');
} catch (var err: unknownerr) {
  var console: Consoleconsole.Console.error(...data: any[]): void[MDN Reference](https://developer.mozilla.org/docs/Web/API/console/error_static)error(var err: unknownerr);
}

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 import fsfs = require: anyrequire('node:fs');

import fsfs.stat('/Users/joe/test.txt', (err: anyerr, stats: anystats) => {
  if (err: anyerr) {
    var console: Consoleconsole.Console.error(...data: any[]): void[MDN Reference](https://developer.mozilla.org/docs/Web/API/console/error_static)error(err: anyerr);
    return;
  }

  stats: anystats.isFile(); // true
  stats: anystats.isDirectory(); // false
  stats: anystats.isSymbolicLink(); // false
  var console: Consoleconsole.Console.log(...data: any[]): void[MDN Reference](https://developer.mozilla.org/docs/Web/API/console/log_static)log(stats: anystats.size); // 1024000 //= 1MB
});

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

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

async function function example(): Promise<void>example() {
  try {
    const const stats: anystats = await import fsfs.stat('/Users/joe/test.txt');
    const stats: anystats.isFile(); // true
    const stats: anystats.isDirectory(); // false
    const stats: anystats.isSymbolicLink(); // false
    var console: Consoleconsole.Console.log(...data: any[]): void[MDN Reference](https://developer.mozilla.org/docs/Web/API/console/log_static)log(const stats: anystats.size); // 1024000 //= 1MB
  } catch (function (local var) err: unknownerr) {
    var console: Consoleconsole.Console.log(...data: any[]): void[MDN Reference](https://developer.mozilla.org/docs/Web/API/console/log_static)log(function (local var) err: unknownerr);
  }
}
function example(): Promise<void>example();

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

請勿阻塞事件循環 Node.js 中的檔案路徑