The way to check if a file exists in the filesystem, using Node.js, is by using the fs.existsSync() method:

const fs = require('fs')

const path = './file.txt'

try {
  if (fs.existsSync(path)) {
    //file exists
  }
} catch(err) {
  console.error(err)
}

This method is synchronous. This means that it’s blocking. To check if a file exists in an asynchronous way, you can use fs.access(), which checks the existence of a file without opening it:

const fs = require('fs')

const path = './file.txt'

fs.access(path, fs.F_OK, (err) => {
  if (err) {
    console.error(err)
    return
  }

  //file exists
})