Node.js stats.atimeNs Property

The stats.atimeNs property is an inbuilt application programming interface of the fs.Stats class is used to get the timestamp when the file is accessed last time since the POSIX epoch expressed in nanoseconds.

Syntax:

stats.atimeNs;

Parameters: This property does not have any parameter, but during creation of stats object {bigint:true} must be passed as options.

Return Value: It returns a number or BigInt value that represents the timestamp when the file is accessed last time since the POSIX epoch expressed in nanoseconds.

Below examples illustrate the use of stats.atimeNs property in Node.js:
Example 1:

// Node.js program to demonstrate the
// stats.atimeNs property

// Accessing fs module
const fs = require('fs');

// Calling fs.Stats stats.atimeNs
// using stat
fs.lstat('./', { bigint: true }, (err, stats) => {
    if (err) throw err;

    // The timestamp when the file
    // is last accessed (in NS)
    console.log("Using stat: " + stats.atimeNs);
});

// Using lstat
fs.lstat('./filename.txt',
    { bigint: true }, (err, stats) => {
        if (err) throw err;

        // The timestamp when the file is
        // last accessed (in NS)
        console.log("Using lstat: " + stats.atimeNs);
    });

Output:

Using stat: 1592654526560650
Using lstat: 1592664546730291

Example 2:

// Node.js program to demonstrate the
// stats.atimeNs property

// Accessing fs module
const fs = require('fs').promises;

// Calling fs.Stats stats.atimeNs
(async() => {
  const stats = await fs.stat(
        './filename.txt', {BigInt:true});

  // The timestamp when the file
  // is last accessed (in NS)
  console.log("Using stat synchronous: "
            + stats.atimeNs);
})().catch(console.error)

Output:

Using stat synchronous: 1592664546730291

Note: The above program will compile and run by using the node filename.js command and use the file_path correctly.

Reference: https://nodejs.org/api/fs.html#fs_stats_atimens