1import fs from 'fs';
2
3const path = './file.txt';
4
5try {
6  if (fs.existsSync(path)) {
7    //file exists
8  }
9} catch(err) {
10  console.error(err);
11}

1// checking existence of file synchronously
2function doesFileExist(urlToFile) {
3    var xhr = new XMLHttpRequest();
4    xhr.open('HEAD', urlToFile, false);
5    xhr.send();
6     
7    return xhr.status !== 404;
8}

1function executeIfFileExist(src, callback) {
2    var xhr = new XMLHttpRequest()
3    xhr.onreadystatechange = function() {
4        if (this.readyState === this.DONE) {
5            callback()
6        }
7    }
8    xhr.open('HEAD', src)
9}